По тонкому льоду

On Thin Ice is a 1966 Soviet spy film directed by Damir Vyatich-Berezhnykh, based on Georgiy Bryantsev's 1961 book, which provided the first authoritative public description of counterintelligence group GUKR. The film tells the story of two NKVD agents who fight foreign spies in the Oryol Oblast before and during the Second World War.