L'Avventura

A woman disappears during a Mediterranean boating trip. During the search, her lover and her best friend become attracted to each other.
Claudia and Anna join Anna's lover, Sandro, on a boat trip to a remote volcanic island. When Anna goes missing, a search is launched. In the meantime, Sandro and Claudia become involved in a romance despite Anna's disappearance, though the relationship suffers from guilt and tension.