The plot is based on a true story told by criminal lawyer Jean-Yves Moyart, in his book "Au guet-apens" : Maître Jean Monier hasn't taken on any criminal cases since he cleared a recidivist murderer. A meeting with Nicolas Milik, a father accused of murdering his wife, touches him and shakes his certainty. Convinced of his client's innocence, he is ready to do anything to defend him against all odds, and especially against himself.