[1] Based on Donald Westlake's novel Two Much, the story involves an indebted Frenchman who meets a pair of beautiful and rich American twin sisters.

Owner of a struggling business in Paris, Matthias Duval stakes all he has in a game of poker and loses.

Matthias then leaves Liz to go on an imaginary business trip to Japan, while "Mathieu" joins his wife Betty and her lonely sister in an isolated seaside house they own, When the twins are out one night, the lawyer Volpinex appears.

Hastily returning from Japan, Matthias resumes relations with his wife Liz and comforts the bereaved Betty.

In fact, the girls knew of his duplicity all along and are happy to live as a ménage à trois.