When two FBI agents showed up on the doorstep of Roman Badanin's California home in the autumn of 2025, they were smiling but the message they delivered was troubling.
Badanin, an exiled Russian journalist who has spent more than two decades investigating President Vladimir Putin and his entourage, could become the target of an attack by a "foreign intelligence service", the agents warned. His wife and four children could be at risk, too.
"I wasn't scared but I was surprised," Badanin, 49, told AFP in an interview in Paris. "They were the first FBI agents I'd ever met."
Along with his colleague Mikhail Rubin, Badanin wrote a taboo-breaking book about the Russian leader's rise to power and private life, titled "The Tsar in Propria Persona: How Vladimir Putin Deceived Us All".
Last month, the French edition won the Grand Prix Strasbourg, a new literary award.
The jury said the 800-page tome reads "like a spy novel", describing the exhaustively researched account of the alleged web of lies, corruption, extramarital affairs and links to organised crime under Putin as both "fascinating and shocking".
"This book is exceptional in more ways than one," said the French publisher, Les Arenes, hailing "the true story of a man who places himself above morality and human laws".
For the authors, the recognition is tinged with regret.
For years Badanin, founder of an investigative media outlet called Proekt, and his team chronicled abuses committed by Putin, his inner circle and Russian security services.
Yet much of the world preferred to look the other way, the authors argue.
Then Putin invaded Ukraine and the West finally began paying attention.
"All the atrocities that the Kremlin routinely committed inside Russia began to spill beyond its borders, on a vastly different scale," they wrote.
Another source of frustration for Badanin is what he sees as the poor quality of some Western analysis on Russia.
He also warned against underestimating 73-year-old Putin, who has been in power since 2000.
"He's become the subject of ridicule," Badanin said.
"But no, unfortunately, Putin is not stupid. And Putin is not, apparently, cowardly."
He estimated that most people around Putin wanted the fighting in Ukraine to stop, saying commanders on the ground understood "the price of war".
"No-one tells us that FSB officers come to Putin and say, 'Let's attack Lithuania' or 'Let's push on to Lviv'", Badanin said, referring to the western Ukrainian city near Poland.
But, in Badanin's view, Putin became a victim of his own ambitions.
"Initially, he wanted a quick victory to strengthen his position in every respect, both at home and abroad."
Putin, he said, had wanted to prove he was a "real man" using the Russian word "muzhik" which carries strong macho connotations.
"Let's spell out some important things about Putin. He is deeply driven by basic impulses -- in the sense that these human passions are not foreign to him but rather very much a part of who he is."
Four-and-a-half years into what has become the largest armed conflict in Europe since World War II, the fighting in Ukraine shows few signs of ending.
European nations fear the Kremlin is preparing to escalate the conflict further in response to Western support for Kyiv.
Putin has now dug his heels in, Badanin said.
"What's going through his mind now? 'Everyone is against me. I can't back down'."
The book is based on interviews with around 300 people including members of Putin's inner circle.
While Badanin built his career exposing corruption in Russia, he was astonished by some of what he learnt during his research.
He travelled to a Caribbean island to meet a Russian lawmaker who arrived on a yacht. The encounter left him struck by the sheer scale of the corruption and the sense of impunity among Russia's political elite.
"We're either idealists or idiots," he told Rubin after the four-hour interview.
Both were driven into exile after FSB officers raided their homes in June 2021.
The following month, Proekt became the first Russian media outlet to be designated an "undesirable organisation".
The team is now working on a documentary about the FSB, which Badanin argues must be dismantled if Russia is ever to have a chance at a democratic future.
As long as the successor to the Soviet-era KGB is around, he said, he will not move his family back to Russia.
"It's the greatest threat to everything that's alive there," he said of the FSB.
Does he have any advice for France's next president, who will succeed Emmanuel Macron next year?
"Remember that everything you do with Putin will, first and foremost, be used by Putin to strengthen his own grip on power in Russia," Badanin said.
"In theory, that could eventually lead to another war."