The harrowing tale of Bill Browder—how an American-born businessman became an enemy of the Russian state, how he has to live in constant fear, never knowing if the long arm of the Kremlin will snatch him, or kill him—is its own kind of daily terror. But what Browder’s story tells us about the way Vladimir Putin operates, and what he might want from this country, should scare us all.

William Browder took his family on vacation in July, though he won’t say where because that is one of those extraneous bits of personal information that could, in a roundabout way, get him bundled off to a Siberian prison or, possibly, killed. For eight years, he’s been jamming up the gears of Vladimir Putin’s kleptocratic machine, a job that seems to often end in jail or death, both of which he’d very much like to avoid. He’ll concede, at least, that his leisure travels took him from London, where he lives, through Chicago, where he changed planes. As he walked through a terminal at O’Hare, he got a call from a New York Times reporter named Jo Becker.

“Do you know anything,” she asked, “about a Russian lawyer named Natalia Veselnitskaya?”

Browder stopped short. “Yes,” he said. “I know a lot about her.”

One of the most important things he knew was that Veselnitskaya had spent many dollars and many hours trying to convince Washington that Browder is a criminal. More than a decade ago, Browder was the largest individual foreign investor in Russia, managing billions in his hedge fund. Then, in 2009, one of his attorneys was tortured to death in a Moscow jail after exposing a massive tax fraud committed by Russian gangsters. His name was Sergei Magnitsky, and Browder has spent the years since trying to hold accountable anyone connected to Sergei’s death. The most significant way is through the Sergei Magnitsky Rule of Law Accountability Act, a 2012 U.S. law that freezes the assets and cripples the travel of specific Russians, many of whom have allegedly laundered millions of dollars in the West.

The Kremlin hates that law. Putin’s hold on power requires the loyalty of dozens of wealthy oligarchs and thousands of complicit functionaries, and their loyalty, in turn, requires Putin to protect the cash they’ve stashed overseas. Putin hates the law so much that he retaliated by banning Americans from adopting Russian children—yes, by holding orphans hostage—and has said that overturning the Magnitsky Act is a top priority.

That’s where Veselnitskaya comes in. As a lawyer, she represented a Russian businessman trying to recover $14 million frozen by the Magnitsky Act. More important, she was involved in an extensive 2016 lobbying and public-relations campaign to weaken or eliminate the act, in large part by recasting Browder as a villain who conned Congress into passing it. That was not empty political spin for an American audience: The Russians really do want Browder in prison. In 2013, a Russian court convicted him in absentia (and Sergei in his grave) of the very crime Sergei uncovered and sentenced Browder to nine years in prison. Later, it got worse. In April 2016, Russian authorities accused Browder of murdering Sergei—that is, of killing the person on whose behalf Browder had been crusading, and who the Russians for seven years had insisted was not, in fact, murdered.

The campaign was oafish yet persistent enough that Browder thought it wise to compile a 26-page presentation on the people behind it. Veselnitskaya appears on five of those pages.

“I’ve been trying to get someone to write this goddamned story,” Browder told Becker on July 8. “She’s not just some private lawyer. She’s a tool of the Russian government.”

But why, Browder wanted to know, was Becker suddenly interested?

“I can’t tell you,” she said. “But I think you’ll be interested in a few hours.”

Browder flew off to the place he won’t name, switched on his phone, and scrolled to the Times website. He drew in a sharp breath.

He exhaled. F***.

Donald Trump Jr. told the Times that the June 9, 2016, meeting had been about adoptions, which demonstrated either how out of his depth he was or how stupid he thought reporters were. If Veselnitskaya had been talking about adoption, she of course had been talking about the Magnitsky Act.

Which meant she’d also been talking about Bill Browder.

He read the story again, closely. Browder wasn’t sure what the implications were. But if he’d known about it in real time—that the staff of a major-party presidential candidate was listening intently to those who accuse him of murder and want him extradited and imprisoned—he would have been terrified.

“Putin kills people,” Browder said to me one afternoon this autumn. “That’s a known fact. But Putin likes to pretend that he doesn’t kill people. So he tends to kill people he can get away with killing.”

Browder did not say this as if it were a revelation. (And technically it’s an allegation that Putin has people killed, albeit one so thoroughly supported by evidence and circumstance that no one credibly disputes it.) Rather, he told me that by way of explaining why he was telling me anything at all: The more often and publicly he tells the story of Sergei Magnitsky, the less likely he’ll be to get poisoned or shot or tossed out a window, which has happened to a number of Putin’s critics. If anything does happen to him, he reasons, the list of suspects would be short.

He spoke softly, methodically, though with great efficiency; not scripted, but well practiced. We were in the conference room of his offices in London. Afternoon light washed through a wall of windows, threw bright highlights onto his scalp, sparked off the frame of his glasses. Browder is 53 years old, medium build, medium height, medium demeanor, and was wearing a medium-blue suit. He does not look like a threat to Russian national security, which the Kremlin declared him to be 12 years ago. Still, there is a hint of steel, something hard and sharp beneath all of the mediumness; if he confessed that he’d served in the Special Forces, it would be a little surprising but not shocking.

It was late September, and Donald Trump had been president for 248 days. In the weeks after the election, Browder was “worried and confused.” Trump has a creepy habit of praising Putin, but he’d also surrounded himself with Russia hard-liners like General James Mattis, Nikki Haley, and Mike Pompeo—secretary of defense, ambassador to the United Nations, and director of the CIA, respectively. Browder war-gamed the Magnitsky Act but didn’t see any way that Trump could kill it—Congress would have to repeal the law—only a chance that he might refuse to add more names to the target list. (Five people were added to the list last January, bringing the total to 44.) He figured the same was true with the Global Magnitsky Human Rights Accountability Act, which President Obama signed shortly before leaving office, expanding the targeted-sanctions tool to human-rights abusers worldwide. The Russians hate that law, too, because having “Magnitsky” in the title reminds the entire planet where the standard was set and by whom.

The first months of the new administration unspooled, spring into summer. Trump’s flirtation with Putin persisted, but with no practical effect. “The Russians got nothing,” Browder said. Congress, in fact, imposed its own sanctions on Russia for meddling in the 2016 election, cutting Trump out of the loop entirely. “I watch this like a hawk,” Browder said, “and so far they’ve gotten nothing. There’s not a single piece of Russian policy that’s gone Putin’s way.”

But then, in July, the Times reported that Veselnitskaya had met with Trump Jr., Jared Kushner, and Paul Manafort, Trump’s campaign manager at the time, in June 2016. That shifted the calculus. “America has been my staunchest ally,” Browder said. “It wasn’t an assumption but a question: Had they flipped my biggest ally?”

That was still an open question when we met in London. Much more had been reported about Trump and Russia. Other contacts and communications were known, and details kept evolving, an endless, sloppy churn of information. There was more, too, about the meeting with Veselnitskaya, which happened two weeks after Trump secured the nomination: It was attended by eight people in all, including Rinat Akhmetshin, who is usually described as a former Russian military-intelligence officer, though that generously assumes that any Russian spook is ever fully retired from the spy game. Browder has another PowerPoint presentation on him. Additionally, Manafort’s notes on the meeting reportedly mentioned Browder by name.

This is all bad. “They were in a meeting to discuss Bill Browder, the Magnitsky Act, and how to get the Magnitsky Act repealed,” he said. “Now, what [the Russians] were offering in return, we don’t know. But if it had just been a courtesy meeting, only one of [the Trump team] would have showed up.”

Maybe no one will ever know what, if anything, the Russians offered. But there’s no doubt what they wanted, and how badly. In a four-page memo prepared for the meeting by Veselnitskaya (and later obtained by Foreign Policy), the Magnitsky Act was inspired by “a fugitive criminal” who ripped off the Russian treasury and then went on a worldwide publicity tour to, apparently, cover it up. “Using the grief of the family of Magnitsky to his own advantage, Browder exposes them as a human shield to distract attention from the details of his own crime,” she wrote. Passage of the Magnitsky Act, moreover, marked “the beginning of a new round of the Cold War.”

That is an assertion as grandiose as it is belligerent. And yet it is not wholly inaccurate. To understand why the Kremlin is so perturbed, it helps to understand Bill Browder. In many ways, he is the Rosetta Stone for decoding the curious relationship between the Trumps and the Russians.

Browder’s grandfather Earl was a communist. He started as a union organizer in Kansas and spent some time in the Soviet Union in the 1920s, where he married a Jewish intellectual and had the first of his three sons, Felix. The family moved to Yonkers in 1932, where Earl became secretary general of the Communist Party USA. He ran for president twice, in 1936 and 1940, and Time magazine put him on its cover in 1938 above the headline COMRADE EARL BROWDER. His fortunes fell in 1941, when he was convicted of passport fraud. His four-year sentence was commuted after 14 months, and he was released into relative obscurity until the 1950s, when he was harassed by the House Un-American Activities Committee.

Bill’s grandmother steered her boys away from politics and toward academics, in which they wildly overachieved. Felix enrolled at M.I.T. at the age of 16, graduated in two years, and had a Princeton Ph.D. in math when he was 20. He met his wife, Eva, at M.I.T., a Jewish girl who’d fled Vienna ahead of the Nazis and spent her teenage years in a tenement with her impoverished mother.

Felix and Eva had two boys. Their first, Thomas, took after his father: University of Chicago at 15, doctoral student in physics at 19. Their second, Bill, did not. He liked to ski and smoke and drink. He got kicked out of a second-tier boarding school and barely got into the University of Colorado, which was fine with him because it was a notorious party school. By his account, he spent his formative years rebelling against everything his leftist-intellectual family held sacred.

“Rejecting school was a good start, but if I really wanted to upset my parents, then I would have to come up with something else,” he wrote in his 2015 book, Red Notice: A True Story of High Finance, Murder, and One Man’s Fight for Justice. “Then, toward the end of high school, it hit me. I would put on a suit and tie and become a capitalist. Nothing would piss off my family more than that.”

He started studying, transferred to the University of Chicago, got into a two-year pre-MBA program at Bain & Company, in Boston. He parlayed that and an essay about Comrade Earl Browder—from communist to capitalist in two generations!—into a seat at Stanford. Out of genealogical curiosity, he began thinking about Eastern Europe. “If that’s where my grandfather had carved out his niche,” he wrote, “then maybe I could, too.” He got a job with a consulting firm and moved to London in August 1989. Three months later, the Berlin Wall fell and the Soviet Union crumbled. Eastern Europe was wide open for business.

His first account was consulting for a Polish bus manufacturer that was bleeding cash. It was miserable work in a miserable little city, but while he was there his translator explained the financial tables in the local newspaper. With the fall of communism, nationalized companies were being privatized and their stocks were offered at fire-sale prices: A company with $160 million in profits the previous year had a stock valuation of only $80 million.

Browder invested his entire savings, $2,000, in Polish stocks. He eventually walked away with $20,000. He’d found his niche.

By 1993, he was in Moscow, investing in staggeringly undervalued stocks: He invested $25 million and turned a $100 million profit. With money that good and almost no Western competition, Browder, in 1996, raised enough cash to open his own fund, Hermitage Capital.

Over the next decade, Hermitage did exceptionally well. The downside, though, was that the economy wasn’t transitioning from communism to capitalism so much as it was devolving into gangsterism. Corruption was endemic. A handful of oligarchs looted and swindled at their leisure. Browder countered by positioning himself as an activist shareholder; he and his staff would piece together who was ripping off what, name names, try to impose a modicum of order on a lawless system.

When Vladimir Putin rose to power, Browder believed he was a reformer eager to purge the kleptocracy. In 2003, for example, Putin arrested the country’s richest man, oil magnate Mikhail Khodorkovsky, charged him with fraud, and displayed him in a cage in a courtroom until his inevitable conviction. In the context of the time, many critics saw the ordeal as a capricious show trial orchestrated by an authoritarian thug.

Not Browder. “I would trust Putin any day of the week,” he told The Washington Post in early 2004. “It’s like being in a lawless schoolyard where there’s bullies running around and beating up all us little people, and then one day a big bully comes along and all the little bullies fall into line. That’s what the state is supposed to be—the big bully.”

But Putin, he discovered, wasn’t pushing for good corporate governance. He was taking over the rackets. Putin put Khodorkovsky in a cage for the same reason Vito Corleone put a horse’s head in Jack Woltz’s bed: to send a message. Oligarchs could steal, but they had to pay tribute.

Oligarchs no longer needed to be named and shamed; they needed to be kept in line and to keep earning. At that point, an activist shareholder like Browder became an expensive nuisance. Browder was kicked out of the country on November 13, 2005.

For a while, he thought the Russian bureaucracy had made a mistake by canceling his visa, confusing him with someone else, perhaps, or misfiling some paperwork. He enlisted the help of British diplomats—Browder had been a British citizen since 1998—to no avail. There had been no mistake. Browder had been declared a threat to Russian national security.

Hermitage Capital remained in business, though, its office run by Browder’s staff while he oversaw operations from London. But in Moscow, the pressure only increased. In June 2007, security forces raided Hermitage and the office of the law firm it employed. They carted away computers and files and, interestingly, all the corporate seals and stamps. At first, none of that made sense.

But then Sergei Magnitsky, a 36-year-old Muscovite who handled tax matters for Hermitage, started digging around. He eventually discovered three of Hermitage’s holding companies had been used by Russian gangsters to swindle $230 million in tax rebates. It was a straight-up robbery of the Russian treasury. The scam wasn’t unheard of, except the amount was perhaps the largest such tax fraud ever uncovered in Russia.

Browder and his staff reported the theft to the authorities and the media in the summer of 2008. They even named suspects, including some of the security officials who’d earlier been involved in the office raids. Nothing happened. Then, a few months later, on November 24, 2008, Sergei was arrested at his home.

He was held for nearly a year in various prisons, overrun with rats and damp with sewage. According to complaints Sergei wrote, he was fed porridge infested with insects and rotten fish boiled into mush. He contracted pancreatitis and gallstones but was refused treatment. Yet he was repeatedly told he would be released if he would recant his allegations and, instead, implicate Browder as the mastermind of the tax scam. He refused every time.

Almost a year after he was arrested, desperately ill, Sergei was handcuffed to a bed rail in an isolation cell. Eight guards beat him with rubber truncheons. A little more than an hour later, he was dead.

Before Sergei was killed, Browder had been lobbying anyone he could think of to pressure the Russians into releasing his accountant. One of the agencies he approached in the spring of 2009 was the U.S. Helsinki Commission, an independent federal agency in Washington that monitors human rights in 57 countries, including Russia.

Kyle Parker, one of the Russia experts there, wasn’t interested. He knew who Browder was—the money manager who’d championed Putin, the guy who’d made the rounds of Western capitals a few years earlier trying to get his visa restored. He assumed that’s what Browder was still after. “Not gonna be able to make it,” he e-mailed a colleague scheduling the meeting. “Unless much has changed, I see this meeting as info only and would not support any action on our part.”

He eventually met with Browder, though, and he listened to the story of Sergei. Parker understood, but it didn’t seem especially uncommon. “I was thinking: Why is Bill trying to suck us into a pissing match between competing criminal groups?”

Parker didn’t even include Sergei in a 2009 letter to Obama highlighting the commission’s most pressing concerns.

After Sergei had been killed, Browder went back to the Helsinki Commission.

Parker told him how sorry he was. He told him that he cried when he heard Sergei was dead, that he read about it through teary eyes on the Metro, riding the Red Line home to his wife and kids. He said he was going to help.

“Here you have this Russian hero almost of a literary quality in Sergei Magnitsky,” Parker told me. “He wasn’t a guy who went to rallies with a bullhorn and protested human-rights abuses in Chechnya. He was a bookish, middle-class Muscovite. I see Sergei metaphorically as that Chinese guy standing in front of the tanks, but with a briefcase. He provided an example for all the other Russians that not everybody goes in for the deal, not everybody is corrupt, not everybody looks the other way when people are swindled.”

What Browder wanted was some form of justice for Sergei, though what form that would take was unclear. He’d researched his options for months. The Russians weren’t going to prosecute anyone—officially, Sergei died of heart failure. There was no international mechanism to hold Russian nationals criminally accountable in another country. “Eventually,” Browder said, “it became obvious that I was going to have to come up with justice on my own.”

He outlined a three-pronged approach. One was media, simply getting Sergei’s name and his death and the reasons for it into the public consciousness. He talked to reporters, and he produced a series of YouTube videos, short documentaries on the people allegedly involved in Sergei’s death.

The second was tracing the money. “They killed him for $230 million,” Browder said, “and I was going to find out where that money went.” It was parceled out to dozens of people, tucked away in Swiss accounts and American real estate and Panamanian banks, some of it held by proxies; part of it allegedly ended up in the account of a Russian cellist who happened to be a childhood friend of Putin’s. By mining bank transfers and financial records, Browder and his staff have accounted for much of it, including $14 million allegedly laundered by a Cypriot company into Manhattan property. (The Justice Department froze those funds in 2013 but settled with the company, Prevezon, last summer for $5.9 million. Prevezon’s owner, a Russian named Denis Katsyv, is represented by Natalia Veselnitskaya. The case did not allege that he had any role in Magnitsky’s death.)

The final prong was political. Browder had heard about an obscure regulation that allows the State Department to put visa restrictions on corrupt foreign officials. But in the spring of 2010, the Obama administration was attempting to normalize relations with Russia—a “reset,” as Obama famously put it. People die horrible deaths every day, and it’s terrible and it shouldn’t happen. But Russia is also a large country with a significant sphere of geopolitical influence and a lot of nuclear weapons. In that context, a dead middle-class tax lawyer wasn’t relevant.

But what if, Parker suggested, they went to Congress? What if the legislature, rather than the administration, took action?

That was also a long shot. Getting any law passed is difficult, let alone one the administration opposes. But Browder told Sergei’s story to congressional committees and individual senators and congressmen, and he kept telling it until the Sergei Magnitsky Rule of Law Accountability Act was passed by both houses of Congress and signed into law 11 days before Christmas 2012.

The act originally named 18 Russians, including bureaucrats implicated in the original scam; investigators Sergei had accused of being involved and getting a cut of the $230 million; jailers who tormented him; and two alleged killers. As more of the stolen money was traced, more names were added to the list. Everyone on it is banned from entering the United States and, more damaging, cut off from the American banking system. That has a ripple effect: Legitimate financial institutions all over the world monitor the Treasury Department list of sanctioned individuals and are loath to do business with anyone on it. “That’s what people hate about it the most,” Browder said. “It makes you a financial leper.”

And that matters to Putin, Browder maintains, because the Russians on the list are not independently wealthy, like, say, Bill Gates or Richard Branson. “They’re dependently wealthy,” he said. “They’re dependent on Putin.” If the deal is that corrupt Russians can keep their cash in return for their loyalty, the Magnitsky Act is an enormous thorn in Putin’s side. If he can’t protect anyone’s pilfered money, what’s the point of loyalty? Putin surely understands that, because he was so transparently rattled: Taking orphans hostage is not the reasoned reaction of a man merely annoyed.

Browder initially wanted to call the law the Justice for Sergei Magnitsky Act. But Parker never took to that. “Banning some corrupt officials from coming here isn’t even close to justice,” he said. “But it’s a legislative monument to Sergei Magnitsky until one day Russia builds a stone monument to him. Because I have no doubt he’ll be seen as the Russian patriot and hero that he was.”

Not quite three weeks after the Times broke the story of Veselnitskaya lobbying the Trump campaign to get rid of the Magnitsky Act, Browder testified before the Senate Judiciary Committee about, primarily, how Russian operatives wield influence and frame their propaganda. Eight years after he’d started targeting a handful of Russian crooks, Browder was suddenly very relevant to a much larger political storm.

He flew home to London after he testified but had to return to the United States in early August. He checked in at an airline counter in Heathrow but was told there was a problem with his visa. He’d been flagged by Interpol, which had issued a red notice on him. It’s basically an international arrest warrant, and it was the fourth requested by the Russians for Browder. Technically, a member nation is supposed to extradite him to the country that asked for the notice. But the British, along with other sensible Western nations, stopped taking Russia’s attempts regarding Browder seriously years ago.

In the end, it was only an inconvenience. But what if he’d been in, say, Finland when that notice popped up? The Finns are fine people, but they also have a 500-mile border with Russia. Would letting Browder go be worth risking an international incident with a bigger, more aggressive neighbor? He can make a reasonable case that, no, he would not be worth it. “I’m very realistic about who’s coming to my defense,” he said. “I am my defense.”

So he’s careful. He avoids countries that might be friendly to Putin. Much of the Third World is out. So is Hong Kong. He’d be fine in Japan, but only if he didn’t fly over Russian airspace. What if the plane has trouble and makes an emergency landing in Novosibirsk? That’s where Khodorkovsky was seized and hauled off to a cage.

Even in London, he’s cautious. He won’t talk about his family or where he lives. He varies his schedule and his route to work every day. He doesn’t eat in the same restaurant twice in succession, or in any restaurant with predictable frequency; Russian agents have reputedly twice poisoned dissidents in London. He told me the British government has rebuffed at least a dozen requests to extradite him, and American intelligence has warned him that Russian agents planned to grab him off the street.

Years ago, a Russian living in London came to Browder’s staff with information about certain wealthy, corrupt people in Moscow. He was cagey and shifty and, at first, it seemed like he might be a Russian agent trying to plant false clues. But his information checked out and Browder learned who he really was. His name was Alexander Perepilichnyy, and he was nervous because he believed he was on a Russian hit list.

On November 10, 2012, Perepilichnyy dropped dead in front of his house in Surrey. There was no obvious cause of death—no heart attack or stroke or aneurysm—and an inquest wasn’t opened until last June. Perepilichnyy wasn’t a well-known dissident, so no one thought to take a hard look when he died. “They got away with it,” Browder said, meaning the Russians. “That’s a perfect example of why you don’t want to be an anonymous guy who drops dead.”

So Browder is deliberately not anonymous. He does not live in cloistered fear. When a car service got confused trying to pick him up for a photo shoot—definitely a way to not be anonymous—we took the Tube a few stops, then walked through Kentish Town to the studio. There was no security, just two men wandering around London. He has hobbies that he asked I not name, but none of them are solitary or sedentary. “One thing I can tell you,” he said, “with the threat of death hanging over you, you live life to the fullest.” He laughed a little.

In this new version of his life, Browder is still most often referred to as a financier, but that’s only marginally true. He gave all his investors their money back, and manages only his own now. Justice for Sergei—and aggravating Putin—is his full-time job. His staff of 11 tracks money launderers, deciphering which flunky is fronting for which oligarch, sniffing out the rest of that $230 million. He lobbies other governments to pass their own versions of the Magnitsky Act. The United Kingdom has one, as does Estonia. Lithuania is close, and Canada passed one in October. “Unconstructive political games,” Putin told a Canadian interviewer immediately after, orchestrated by “the criminal activities of an entire gang led by one particular man, I believe Browder is his name.”

And Putin wasn’t finished. A week later, Russia slipped another red notice into Interpol’s system. For the second time in three months, Browder was temporarily barred from entering the U.S. It’s relentless, Putin clawing at him, thrashing. “Their main objective is to get me back to Russia,” he said. “And they only have to get lucky once. I have to be lucky every time.”

“Everything Bill’s done has cost him tremendously,” Parker said. “It’s cost him money, restricted his personal freedom. And he didn’t have to. He was out of Russia. He could have done what many did and walked away. Bad things happen, right? But here’s a guy who’s proven whatever he needed to prove to himself. He made his money. Now here’s a way to find meaning. It’s also a debt of honor.”

No, it’s more than that. “It’s penance,” Browder said. Sergei Magnitsky was an ordinary Muscovite who happened to work for an American who annoyed Vladimir Putin. “Sergei was killed because of me. He was killed instead of me.” He let that hang there a moment. “So, yeah, it’s all penance.”

Sean Flynn is a GQ correspondent.

This story originally appeared in the December 2017 issue with the title “Putin Enemy No.1.”