Harry Palmer (Michael Caine), who has left MI5 to work as a private investigator, is told by a mechanical voice on the phone to take a package to Helsinki. The package contains six virus-laden eggs that have been stolen from the British government's research facility at Porton Down. In Helsinki, he is met by Anya (Françoise Dorléac), who takes him to meet her handler, Harry's old friend Leo Newbigen (Karl Malden). Leo is in love with Anya, but Harry sees that she is only pretending to reciprocate.