The film portrays the events on the day King Henri III of France arranged for Duke Henri de Guise to be murdered.
Gribiche, a young boy whose mother is a war widow, gets adopted by a rich woman. She wants to turn him into a perfect gentleman, but soon he feels unhappy.
Fernand Espitalion is miserable as totally whipped husband of a dragon 'passed on' -like cloths- by his late cousin. She often leaves him waiting outside like a dog when she does business. While she sees a notary about an inheritance, he's seduced to a bar by a shady man. The rogue gets Fernand drunk, knocks him out and switches costumes and papers. He's now Robert Durand, a voluntary Foreign legion recruit. After failed attempts to explain, he tastes military life and finds it less disciplined and more enjoyable then, marriage. But will that last when his wife tracks him and his unit is sent to action in tribal Algeria?
