In this French comedy, a toy inventor travels to the factory of his childhood friend, now an industrial magnate, and tries to persuade him to lend financial backing to his newest invention. Unfortunately their reunion is marred by the reopening of old emotional wounds, but fortunately, the inventor's wife smooths things over. Later she discovers love letters written to her adolescent daughter. Trouble ensues when the toymaker begins suspecting his old pal, the industrialist, of writing the letters. He then blackmails his pal with the letters. When his daughter finds a new boyfriend, the inventor abandons his extortion scheme. The two old pals then reconcile and go into business together.