Set in 1950s Belgium at a boarding school, follows seventeen-year-old Laurent Matagne who thinks he recognizes in his French teacher, nicknamed Vapeur, his father who disappeared during an air raid in 1940. Vapeur is eccentric, mysterious, disturbing and brilliant and gives his passion for literature so strongly that Matagne wants to become a writer. Matagne and his friend Boulette decide to launch an investigation. As they build a plot in order to confound Vapeur, Matagne devises at the same time his first novel.