Machinist Fedor Morgunov awaits for his assistant, to ward off the composition of 2 locomotives, a train and platform to the Belyayevka repair station. Suddenly, because of the heart attack he looses consciousness and falls, putting his hand on the lever. The train starts to move spontaneously, picks up speed and becomes unmanageable. To avoid a collision, the controller gives him the green light. However, no one knows that there are people in the train. A PTU student Alexey Nechaev was let in by the driver, Vlad, Galya and Marina go "stowaways." The boys became suspicious only when the train is passing Belyaevka. From the window they see that the locomotive’s head is on fire. Alex decides to get to the machinist’s cab on the roof.