This season sees dramatic changes in La Brigade Criminelle. We introduce Maigret's boss and mentor, Director of Police Xavier Guichard. Guichard has become suspicious of Maigret's growing fame and decides to 'take him down a peg.' One of Maigret's colleagues leaves, another is transferred by Guichard and replaced by a former Internal Affairs officer, George Bonfils who immediately makes himself unpopular with Maigret's core team. This internal turmoil is the backdrop for daring new adaptations of three of Georges Simenon’s best-known Maigret novels: The Hanged Man of Saint-Pholien, Maigret’s Revolver, and The Yellow Dog. As Maigret investigates cruel and heart-breaking crimes, he will find that the line between guilt and innocence can be impossibly blurred. He will have to reach deep into his heart to work out his own unique form of justice, for victims and perpetrators alike.

Maigret investigates in Concarneau where the passage of a yellow dog accompanies a series of murders, sowing terror in the population. The police seem helpless. It must be said that it has no significant evidence.