As romances go, they don’t come a lot less orthodox than this one. “Alex” (Denis Lavant) is a vagrant who finds a berth of a night on the Pont Neuf over the Seine that has been closed for renovation. He survives on a diet of drugs and alcohol and has no real friends beyond his dealer on the bridge. One night he discovers a woman sleeping in his spot. Neither man knows quite how she got there, but “Hans” (Klaus-Michael Grüber) vows to send her packing next morning. When that time comes, however, “Alex” discovers that “Michèle” (Juliet Binoche) is not only an artist, but that she has sketched…