Sébastien, a conscientious and professional train inspector, dreams of being transferred to the South of France. To validate his transfer, he has to make one last routine run under the supervision of Madeleine, a slightly sociopathic inspector who won't let him go. That's when everything goes wrong: between a driver who thinks he's driving a fighter jet, a jealous colleague and passengers who are each crazier than the last, what was supposed to be a formality turns into the worst trip of his life.