Bob Darling is on the fastest train in Europe with a pretty young woman named Carla by his side. He ruminates on his mortality, the drugs he takes to keep control of his bladder, and whether Carla will mourn him when he dies. Darling thinks back to when he met Carla. She was drunk on another train, and he took her to a cafe and propositioned her. They ended up at her place, in bed, where he cried with sorrow, overtaken by his strong sensations of desire, hope, and virility.

In Europe, he has specific plans for their trip, none of which Carla objects to. Yet, once in each city, she had turns out to know exactly what she wanted to do, which happened to be the opposite of what Bob likes or has planned. Injured by this and upset that she is not as complacent before, Bob writes but does not send a postcard to the woman he is truly in love with, Paula, who is his accountant's wife. Bob and Carla get drunk, and after she falls asleep, he reads her journal, which reminds him of an argument they'd had.

He had told her about an occasion where Paula had presented herself naked to him. He and Carla got into a conversation about the difference between nakedness and nudity, and which was more artful or natural. The memory begins to devolve into something more dreamlike, and the story cuts back to the train.

Carla wakes up, and he reminds her that they're supposed to eat dinner in an hour; his highly anticipated full dinner on the fastest train in Europe. Carla objects, saying she can't eat at 5:30, and Bob becomes agitated and reminds her that he'd been planning this for a month, and that she'd agreed to the plan back then. Carla apologizes for being difficult but goes off to the bar for a drink. Bob yells after her, "Take the River Styx to hell!"

As he eats Carla's portion of the meal, Bob finds that he is glad she left. He canvasses the situation objectively — he is on the fastest train, eating an above-average meal. Finally at peace, he falls asleep, soothed by the motion of the train.