"Fone Kvas is a timeless, true document of literature about the real and timeless pain of human beings" - FAZ
A distinguished scientist is arrested in a provincial Soviet-Ukrainian town for belonging to an organization he has never heard of. He is threatened with torture, and suspects he will not be able to endure it. So he develops the idea of pretending to be the "Fone Kvas" (a Yiddish term for a fool or "idiot") in front of the NKVD officers, making wild and implausible "confessions" in the hope of being convicted quickly, but then appealing and showing that everything he has confessed to is completely untenable technically and scientifically, so that he will eventually be released for "erroneous" arrest.
He puts his plan into action. He tells of legendary acts of sabotage, draws convoluted diagrams. The more insane and bizarre his explanations become, the more pleased his investigator appears.
And in the end, everything turns out quite differently than the defendant expected. The insane reality of Stalinist terror will far surpass the fabricated fantasies of the "Fone Kvas".