Boston, 1962. Several elderly women are strangled, apparently by the same unknown assailant. An investigation ensues, but clues lead nowhere. Then the strangler starts to attack younger women. John Bottomly (Henry Fonda) is assigned to direct a more intense investigation, interviewing even the remotest suspects. Meanwhile, the murders continue. Dianne Cluny (Sally Kellerman) survives an attack but remembers only that she bit her attacker's hand. When Albert DeSalvo (Tony Curtis) is caught breaking into an apartment, his mental capabilities are questioned. He goes to the hospital for observation, and there someone notices a bite mark on his hand...