Shy young Marcelo Mastroianni ambles across a bridge one evening, where he meets a strange but alluring girl (Maria Schell) who is awaiting her lover. This chance acquaintance is the first strand in a complex web entrapping Mastroianni in a dreamlike world of flashbacks, flashforwards and false visions.
The girl, suspecting that her lover is staying at a nearby hotel, asks Mastroianni to deliver a note to the errant swain. He agrees--then destroys the note, setting the plot in motion. Updated from a 19th century story by Dostoyevsky, White Nights (Le Notti Bianche) was later refilmed by Robert Bresson as Four Nights of a Dreamer.