A short synopsis from imdb:

After World War III Paris is lying in tatters. The earth has been contaminated and survivors of the war have to live underground imprisoned by the victorious nation (it's never said explicitly which nation that is, but they are talking German). Scientists are looking for a way to secure the survival of mankind by exploring the possibilities of time traveling. In the process one of the prisoners, who has a strong connection to the past because of a recurring dream of his childhood, serves as their guinea pig. As the experiments go on the time traveler falls in love with a woman from the past and comes face to face with the childhood memory he's been obsessed with all his life.

Director: Chris Marker. Beautiful signing by the Choirs of the Cathedral of St Alexandre Newski. "Music from Russian Liturgy of the Good Saturday."

28 minutes