The Executioner (1970 film)

The Executioner is a 1970 Technicolor cold war spy thriller British film in Panavision, starring George Peppard as secret agent John Shay who suspects his colleague Adam Booth, played by Keith Michell, is a double agent. In the film, Peppards character tries to prove the double role of his colleague to his spymasters and when he fails to do so he kills him. It was produced by Charles H. Schneer for Columbia Pictures and filmed in Panavision and Technicolor.

Shay assumes the identity of Booth, and, with the assistance of Booths widow Sarah Joan Collins and his own girlfriend Polly Judy Geeson, he launches into an investigation to uncover Booths connections. Shay maintains a romantic relationship with both women. Booths wife is the romantic interest of Shay and British scientist Philip Crawford George Baker, who provided information to Shay about Booth being a double agent. Shays superiors are Col. Scott Nigel Patrick and Vaughan Jones Charles Gray. Polly assists him in his investigations by providing him with information apparently confirming his suspicions.Shay finds a plane ticket in Booths pocket which he then uses to fly to Athens along with Booths widow, who is unaware that her husband has been murdered by Shay. Upon arrival in Athens, Shay assumes Booths identity and subsequently goes to Corfu, where he is captured along with Sarah by Soviet agents who want Crawford in return for the freedom of their captives. A CIA agent under the name of Professor Parker Alexander Scourby manages to free them both. Colonel Scott Shays superior reveals that Sarahs husband was indeed a double agent who was used by MI5 to supply the Soviets with false information. ........

Source: Wikipedia