Chloe receives an unexpected offer; a television program uncovers a new lead in the abduction case of Adele and her twin sister Camille, causing the case to be reopened.

Chloe must make one of the most difficult decisions of her life; Adele struggles to reconnect with Camille after more than a decade of separation and trauma.

While the team struggles with Chloe's replacement, an over-confident criminologist with little actual experience and even less tact, it falls to Adele to unravel the disappearance of a young girl.

Adele's first investigation involves a killer in a horrible mask, popularized by a viral advertising campaign; the mask has been used in recent violent attacks, and the team will have to put on their best costumes to hunt the clown.

Called to school after Lucas is in a fight, Rocher manages to stop a young man jumping from a building; the boy is the one Lucas was fighting, Rocher takes him home to talk to his mother -- but she has been dead at home for days.

The team is called to investigate the death of an old woman who was hit by a car, poisoned and stabbed three times.