Mika, heiress to a Swiss chocolate company, is married to celebrated pianist André and stepmother to his son, Guillaume, whose mother died in a car wreck on his tenth birthday. Their lives are interrupted by the unexpected arrival of Jeanne, a young woman who has learned she was almost switched with Guillaume at birth.

Betty and Victor are a pair of scam artists. One day Betty brings in Maurice, a treasurer of a multinational company. Maurice is due to transfer 5 millions francs out of Switzerland, and Betty is convinced he plans to steal that money.