One Night... a Train (1968)

Mathias is a Belgian linguist, living with French theatre producer Anne. After a quarrel about moral questions, they take a train to attend a congress. While Mathias sleeps, Anne disappears. The train stops in the middle of the country and Mathias gets off the train with an older man, Hernhutter, and a young one, Val. The train moves off without them being able to catch it up. They will find a village, but cannot get any help because they do not understand a word of what the inhabitants say...