The Killer Is on the Phone (1972)

When a beautiful actress returns from a short trip to London, a mysterious man begins to stalk her. As she slowly turns the corner, she sees him and faints. Hours later she awakens, unable to recognize her own husband an friends. She only remembers seven years before, when her boyfriend was brutally and mysteriously murdered. Now her amnesia is convenient for a killer, as the mystery man waits for the right moment to strike.