Cold Eyes of Fear (1971)

Against a backdrop of Swingin' 60s London a young playboy type "steals" a beautiful Italian girl from her elderly date and suggests she comes back to his place for some good times. "His place" being owned by his father, a rich and respected solicitor. Unfortunately a couple of criminals have plans of their own, one for money, the other for revenge, and the lovers end up prisoners in a tense siege situation