Irča Miňovská, the daughter of a car factory director, meets mechanic Lexa Hora by chance. They fall in love, but Irča's father does not want his daughter's unequal relationship and decides to send Irča to a boarding school so that she cannot see Lexa. Lexa leaves the plans for her new engine with her boyfriend Harry Peters at the factory, resigns, and leaves to forget about Irča. Director Miňovský would like to produce a new type of engine, but Lexa is nowhere to be found...