The Man Outside (1967)

McLean is called back to London where he gets fired after sticking up for his assistant, who's caught selling information to the Russians. Soon he's contacted by George Venaxas a Greek operative who want's to sell information on the whereabouts of a Russian secret police official hiding in London. McLean hesitates, but agrees. The plan backfires when both the CIA and KGB are willing to do anything to get their hands on the Russian defector. Venaxas is murdered, and a trail of double crosses follows.