When the young Jeanne and her future husband Claude fell in love, it was forever. And like lovers eternal, they swore a secret pact. It was as magnificent in its innocence as unthinkable... "If I'm unfaithful, promise to kill me", they said to each other.
Years have gone by and perhaps Claude has forgotten the pact. Not only is he unfaithful to Jeanne, he boasts about it. Jeanne is charged with his murder. Obviously she could plead a crime of passion. Her brilliant Parisian lawyer expects nothing better. But she won't. Strangely indifferent, Jeanne stands by the truth. It was a crime of love, a crime of fidelity, ordered by her husband.
At first Jeanne is alone. No family to support her, she only infuriates her lawyer. Moral support comes from an unexpected quarter, Charlotte, the lawyer's young lover.