DS Mary Jane "MJ" Croft and her newly assembled team are assigned two separate investigations; the disappearance of a young autistic boy's mother and a man who appears to have stolen a large sum of money from his fiancée and subsequently fled.

MJ and Jason probe the disappearance of a girl following a night out with friends; Amy reopens the investigation into the disappearance of MJ's sister and makes a shocking discovery that brings MJ further heartbreak.

Jason is assaulted by an irate husband whose wife has disappeared, but the woman turns out to be a "serial missing person," having vanished several times before; Amy investigates the disappearance of a witness in a criminal trial.

MJ investigates the disappearance of a lawyer, who seems to have simply vanished while playing in the park with his young daughter; a young woman approaches the team for help in finding her abusive father, whom she hasn't seen since she was 16.

MJ believes that a businessman's financial problems may have been a factor in his mysterious disappearance; as Amy interviews a possible witness, she finds herself in unexpected danger; MJ finally comes face to face with her sister.

MJ investigates the disappearance of a 6-year-old girl who appears to have been abducted by her biological father; Amy tries to reunite a father and son who have drifted apart; MJ is forced to deal with the reappearance of her father.