Chêne is a famous personal trainer who has achieved considerable professional successes. But he is also a compulsive gambler who has amassed colossal debts. At the end of her tether, his wife leaves him. Caught in a stranglehold by his creditors, Chêne accepts a contract that can save him: to coach Marmignon, without the latter knowing it. Marmignon is a very peculiar director who seems to be the most untrainable person imaginable.