A mysterious figure known only as "The Visitor" appears in the lives of a typical Bourgeoisie Italian family. His arrival is heralded at the gates of the family's Milanese estate by an arm-flapping postman. The enigmatic stranger soon engages in sexual affairs with all members of the household: the devoutly religious maid, the sensitive son, the sexually repressed mother, the timid daughter and, finally, the tormented father. The stranger gives unstintingly of himself, asking nothing in return. He stops the passionate maid from committing suicide with a gas hose and tenderly consoles her; he befriends and sleeps with the frightened son, soothing his doubts and anxiety and endowing him with confidence; he becomes emotionally intimate with the overprotected daughter, removing her childish innocence about men; he seduces the bored and dissatisfied mother, giving her sexual joy and fulfillment; he cares for and comforts the despondent and suffering father, who has fallen ill.