Henri and his brother Paul attend the reading of their uncle's will, and learn that their Aunt Rosalie inherits everything, but that after her death the two nephews are to share the income from the estate. The excitement of the two brothers is tempered by their present lack of resources. Rosalie has little regard for either of her nephews, and she determines to outlive them both. Paul decides to win over his aunt, and he soon moves in with her. The two brothers then look for a way to kill her without arousing suspicion.