A Venetian musician at La Fenice theatre is affected by an incurable disease. By chance he meets his ex-wife who is now living with another man. She

　　美国游客山姆隔着美术馆的玻璃窗，瞥见一宗企图谋杀，他的及时出现让凶手逃走了，获救的女子芳名莫尼卡。不久，山姆仿佛受了蛊惑似的对这宗谋杀着了迷，他决定追踪凶手的下落，这自然让他的女友朱丽娅很不快；而同时他和女友也开始接到威胁电话……