Four Nights of a Dreamer is a loose adaptation of Dostoyevsky's novella White Nights, with the action transposed from 19th century Russia to modern-day France. One night, Jacques (Guillaume Des Forets), a young man with artistic aspirations, sees a girl (Isabelle Weingarten) trying to commit suicide by jumping from a bridge.
When he prevents her from jumping, Marthe tells him that she has become desperate waiting for her lover, who left her almost a year ago but promised to return. Jacques asks Marthe to meet him by the bridge the next night and the girl agrees.
They spend the following three nights wandering through Paris, and Jacques tries in vain to cure Marthe of the memories of her elusive lover. The same story was previously filmed by Luchino Visconti as Le Notti Bianche.