In Michelangelo Antonioni's classic of Italian cinema, two lovely young women, Claudia (Monica Vitti) and Anna (Léa Massari), join the latter's lover, Sandro (Gabriele Ferzetti), on a boat trip to a remote volcanic island. When Anna goes missing, an extensive search is launched. In the meantime, Sandro and Claudia become involved in a romance despite Anna's disappearance, though the relationship suffers from the guilt and tension brought about by the looming mystery.