Professor Bower, an American physicist, is effectively blackmailed by a shady CIA agent named Adams to help the CIA obtain secret microfilm from a defecting Russian scientist. The reluctant Bower travels to East Germany undercover as an antiques collector where he encounters Heinzmann, an East German fellow physicist, who is also a secret agent. Heinzmann is aware of Bower's meeting with Adams and his intention to steal the microfilm, however their mutual respect for one another's tactics complicate the proceedings.