Whatever possessed Guillaume Neuville to invite his ex-wife Aude and his current wife Caroline to his rich Aunt Camilla Tressilian's house in Pointe-aux-Mouettes to spend the end of summer vacation? Friends they will never be.

It was completely foolhardy for, although these two women who have nothing in common have yet to tear each other to pieces, although they hold back for the moment, things won't stay that way for long. Two Mrs Neuville beneath the same roof is one too many.

Zero Hour approaches, that moment when all converges for the perfect crime to be committed right down to the last detail.

Reluctant at first to welcome two Mrs Neuville in her home, Camilla Tressilian finally accepts the idea. She knows there is no fighting the evolution of modern life.

A magistrat's widow, she is very open-minded and sharp-witted, demonstrating a mocking brusqueness that woman with experience often possess. She is torn between her fondness for Guillaume, who she has raised like a son, and the tenderness she feels for Aude, a young, sensitive woman who keeps her feelings and emotions well hidden.

This strange family reunion takes a tragic turn when Mrs Tressilian is found murdered in her bed one morning, her skull shattered.