He meets a stranger on a train. The stranger--Charles Bruno--asks him to join him for dinner and a couple of drinks. Guy doesn't really want to be social. He's feeling cranky and anti-social. He's thinking about his wife, Miriam, who is carrying another man's baby, and his girlfriend, Anne, who happens to be going to Mexico on vacation. He isn't in love with his wife--they've been separated quite a while. He's anxious to get a divorce more than anything else. He's not at his emotional best though. So reluctantly, perhaps to avoid thinking or over-thinking things, he agrees to spend some time with this stranger. This was his first mistake, the mistake that would cost him almost everything in the end.