Kerttu Nuorteva, a Finnish-born Soviet citizen and spy, was dropped into Finland by parachute in February 1942. She operated undercover in Helsinki until September 7th when she was arrested after a mistake she had made.

The Interrogation is, as the title reveals, the story about her interrogations that were conducted by three consecutive men. At first, they got no results. Kerttu, whose true identity is slowly revealed, refuses to believe when she is told about the cruelty of Stalin´s killing machinery that also targeted Finns. Little by little, her defences start to crumble as the World War is irrevocably turning in favour of the Soviet Union.