A drama teacher works as an extra in the cinema: he has to milk a cow. Left alone with the animal in the studio, he is forced to bring it up to his apartment. The police, the Humane Society and the government get involved.

For fun and to dazzle his wife, the novelist Morgan steals a ring and gets rid of it in the costume jewelry section of a supermarket. Sophie buys the diamond, which forces the novelist to embark on crazy adventures to recover the jewel.

On the verge of death, a man entrusts Inspector Burma with an address. Burma conducts a difficult investigation with many twists and turns, which takes him from Lyon to Paris, following in the footsteps of the members of a mysterious business firm.