On the evening on January 23rd, Viktor Filinkov, a twenty-three-year-old software engineer, was at the departures terminal in Pulkovo Airport, in St. Petersburg, waiting to board a flight to Minsk. From there, Filinkov planned to catch a connection to Kiev, where his wife, Alexandra, was living. He never made it. Filinkov was approached by several men who identified themselves as agents from the F.S.B., a successor agency of the K.G.B., and took him to a waiting dark-blue minivan. What happened next, according to Filinkov, was a five-hour-long torture session, which ended with Filinkov in jail, awaiting trial on charges that could send him to prison for up to ten years.

Filinkov is formally accused of belonging to a terrorist organization, part of a sprawling case against nine young men in St. Petersburg and Penza, a town four hundred miles southeast of Moscow, who, to varying degrees, identify as anti-Fascists or anarchists, or have overlapping friends in those communities. Those detained, according to the F.S.B., have been planning a violent uprising, aimed at “stirring up the masses for further destabilization of the political situation in the country.” The F.S.B.claims the group calls itself Syet, or the Network.

All records regarding the case are sealed, which means that the details of the investigation remain unknown, but the little information that has leaked suggests a plot as fantastical as it is unlikely. The F.S.B. claims that Filinkov and his co-conspirators were planning to set off bombs ahead of Russia’s Presidential election last March, and also during the World Cup, which starts on June 14th and will be held in eleven Russian cities, including St. Petersburg and Saransk, ninety miles from Penza. Among their alleged targets was the Lenin mausoleum, on Red Square.

Human-rights groups, in addition to friends and supporters of the defendants, dismiss the purported plot as a fiction, and say several of the young men were brutally tortured. They believe that overzealous F.S.B. officers essentially invented the Network as a way to impress their superiors, as Russia prepares to host a safe and secure World Cup designed to dazzle a half million foreign visitors and billions of viewers worldwide. Several of those who know the defendants told me that, naturally, those interested in anarchism—along with anti-Fascism and leftist economics—were liable to discuss revolution as a political process, but to suggest that those arrested formed some sort of coherent underground cell, let alone one dedicated to an armed coup, is nonsensical. “I can’t imagine an anarchist who doesn’t talk about some future revolution,” one friend told me. “But to say they wanted to blow up the Lenin mausoleum—it’s a K.G.B. accusation. It’s silly, embarrassing even. What could this possibly have to do with revolution in 2018?”

When I spoke with Vitaly Cherkasov, Filinkov’s lawyer, he wholly rejected the idea that the young men were plotting to overthrow the Russian state. (Equally unlikely, he added, is the F.S.B.’s claim that they wanted to establish an “anarchist government,” a paradoxical impossibility to most anarchists.) If they had some discussions, he said, they represented nothing more than young people debating ideas and sharing utopian fantasies. Cherkasov reached for an analogy from Russian history to explain the case: “The country went through something like this in the nineteen-thirties, when the special services uncovered all sorts of cells supposedly plotting to overthrow the state, and these people were imprisoned and shot—and then, later, it turned out that most of them were innocent, and were rehabilitated.” It is an overly dramatic and, thankfully, not all-that-fitting comparison, but the notion of a number of people being picked up off the street and tortured to admit membership in a revolutionary cell that may well not exist has the ring of secret-police tactics of a century ago.

When I met Cherkasov in St. Petersburg, he told me about visiting Filinkov in the pretrial detention facility that abuts the city’s F.S.B. building. At that meeting, Cherkasov said, Filinkov pulled down his pants, revealing his right thigh, which was covered in dozens of ruddy keloid spots, a spray of burn marks left by repeated strikes from an electric stun gun. Cherkasov said that Filinkov told him that the F.S.B. agents first took him from the airport to a polyclinic, for a checkup. It was a grim moment of pseudo-concern: the reason, Filinkov came to understand, was to make sure his body could withstand the tortures to come. Back in the van, Filinkov was handcuffed. One agent pulled his wool cap over his face; another began to strike him with heavy blows. Filinkov panicked—at which point his body was jolted with the first electroshock.

Over the next five hours, Filinkov was driven around the outskirts of St. Petersburg, while being beaten and repeatedly shocked with the stun gun. He later described the ghoulish process in a jailhouse diary entry, which he publicly released: “They asked questions. If I didn’t know the answer, they hit me with electric shocks. If the answer didn’t correspond to their expectations, they hit me with shocks. If I tried to think or formulate, I was hit with electric current. If I forgot what they said, I was hit with the current.” Some of the questions were impossible to answer (“Where are the weapons?”), but others he tried to answer factually (basic details about his wife and friends).

In addition to his lawyer, Cherkasov, Filinkov was visited in jail by two members of St. Petersburg’s public monitoring commission, an independent body whose members visit detention facilities and check on prison conditions. Yekaterina Kosarevskaya, who is twenty-six, and Yana Teplitskaya, who is twenty-seven, are both mathematicians; their work on the commission is formally a volunteer pursuit, but it has grown into a kind of civic duty that takes up much of their time.

I met Kosarevskaya and Teplitskaya in a café along one of St. Petersburg’s many charming canals, which wind languidly through the center of what is known as Russia’s northern capital. The World Cup will be held during the city’s famed “white nights,” when, because of the northern latitude, a spectral twilight lingers in the sky until well after midnight. They told me that Filinkov showed his wounds to them, too, and that he added more details to what he had told Cherkasov. He spoke of how he was visited in jail by one of the F.S.B. agents who tortured him, who alternated between apologizing for using force (“You know, I don’t like this myself!”) and making further threats. (He suggested that Filinkov could be moved to a worse jail, where “your cellmate will beat you to death, and no one will even hear.”) The F.S.B. agent at one point alluded to prison rape, asking Filinkov, “Is your asshole raw yet?” At night, Filinkov would have nightmares of his torture and remember new details: the license plate of the car that drove him around St. Petersburg, how the seats inside were arranged, bits of conversation among the F.S.B. officers.

When we spoke, Kosarevskaya said that she was struck by how Filinkov said he was tortured to extract a confession during the first minutes of his detention, and then he was tortured to produce the exact formulation of that confession, which was provided to him by F.S.B. agents.