Un alibi: A group of friends who have known each other for many years meet at Max and Lucie's house to celebrate Lucie's birthday. When they arrive, the three guests discover Max kneeling in front of the body of his wife who has been murdered. He is sure that the police will charge him because everything accuses him. Convinced of his innocence, his friends decide to give him an alibi. But the investigation tightens around Max...