A very well-respected Swiss professor stops a woman from jumping off a bridge to her death. She leaves him, with her coat, which contains a small autobiographical book and a train ticket to Lisbon, leaving in 15 minutes. He goes to the train station, looking for her, but when the train is leaving, without her, on a whim - he has never done anything like this - he boards the train, and reads the book all day and night, thus leaving him with a hundred questions and the desire to meet as many of the people in the book who are still alive; he is completely entranced by the book and the people in it.
After being knocked down by a bicyclist, who breaks his thick glasses, an optometrist, who gives him new glasses, helps him put faces to names, and the answers to his questions, via her uncle whose hands were beaten savagely - he was a beautiful pianist - in return for not answering the police's questions. There was a revolution, a coup, in 1973, in Portugal. All the professor has with him is his American Express card and his mobile phone (which never needs charging), and a new friendship with the optometrist.
After all his questions have been answered and after he has seen all the people who are still alive, it is time for him to leave, but he is hesitant. The optometrist, who has come to the train station to see him off, can see this, and because she has fallen in love with the professor, not that he would know this - he has a low opinion of himself, mostly due to his ex-wife who often put him down in front of people ("She thinks I am boring, " the professor says, and later, the optometrist says to the professor, "You are not boring, " and he starts to believe her) - she says, "Why don't you stay?" and the professor is caught between two worlds, and as he faces her and her words, the film ends, with both of them frozen.