Newly promoted Lieutenant Valentine Ventura finds herself working with famous Captain Antoine Thomas who just came back from his medical leave after the tragedy he lived a few months ago : victim of a car crash that killed both his wife and the child she was bearing, Antoine Thomas spent several months in the hospital, and is now back in a wheelchair after losing function of his legs. Working on the case of a murdered young journalist, the two detectives succeed in arresting her colleague, whose guilt is undeniable. Multiple elements even indicate that they just caught a serial killer; although he admits he killed the young journalist, their suspect didn't commit these other murders, and seems to be the victim of a manipulation.

Franck wants a quiet life and a fresh start. After 15 years of a failed theatre career, he finds a seemingly perfect job: museum guard. But that is before he meets Sybille, his neurotic colleague.

Paris, France, 1963. A couple have an argument in a bar. A young man sitting nearby takes the opportunity to talk to the girl and tells her what their life together could be if she accepts to run away with him, now.

In 1991, 24-year-old Detective Alexandre Falco has it all, a loving wife, a new-born daughter and his dream job. But one day out in the field, he is shot in the head. Falco opens his eyes again 22 years later to a changed world, where everything he once had is no longer as it was.

Chloé Saint-Laurent is a profiler and works with a police team to solve murders in Paris. She's very sweet, she wears very colored clothes and a huge yellow bag. She looks like a little girl who need a doll, but she's very smart and a very good profiler. Step by step, she fit in the team and her colleagues, very reserved at first, became her best friends.