The TV series "Tandem" tells the story of two experienced French detectives working together. Lea Soler heads the criminal investigations department in Montpellier. She is intelligent, strict, and ambitious. However, recently she has been forced to work alongside the brilliant and uncontrollable police officer Paul Marshal. The problem is that these two were once married. For the sake of their work and raising their children together, the couple must set aside old grievances. Especially since a new mysterious murder has just occurred in the city.