A father searches for his son, who has been missing since WW II, in post-war Poland. In his quest for the truth about his son, the father is forced to contemplate the elusive and coded nature of truth itself.
In the nineteenth century, a young couple head to the countryside to spend the weekend together. On the train they encounter a mysterious Englishman heading for the same destination. Suspicious of this individual, they take the room next to his - the titular Blue Room - and a mystery ensues...
The Italian soldier Giuseppe Santucci, on his way home from the Russian front, during World War II (in 1943), has his machine gun stolen in Warsaw. Afraid of consequences, he stays in Warsaw and occupies a flat of the Polish girl Maria, whom he suspects of stealing weapon. Maria indeed is an active member of the Polish resistance, contrary to her brother, Staszek, a painter, who only wants a calm living. In a course of funny events, Giuseppe falls in love, and, along with Staszek, becomes a hero of the Polish resistance.
An actress travels from Warsaw to Paris and during the trip reflects on the last few years of her life. It goes back to the German occupation and her hiding of a fellow actor who has supposedly killed a collaborator.