After meeting the twins' parents, Lisa is shocked to discover that her connection to the family might be more than just professional. As the complications within the investigation grow, the hunt is on to find the twins before it's too late. Lisa must also deal with her own family's problems when daughter Abbie is suspended from school.

With the Meredith family reeling from Dylan's death and Sean's arrest, Lisa is charged with finding his alibi and makes a game-changing discovery. Suspicions are raised about another Morecambe resident's involvement with the twins and the police rush to find them. Abbie grows closer to newcomer Vincent, whilst Rob agrees to take on a risky dare. Frustrated by the police investigation, Sean takes matters into his own hands.

When main suspect Nick goes missing, Lisa is concerned about Sean's possible involvement. The discovery of a key piece of evidence provokes a number of new theories and the police begin to look more closely at other members of the Meredith family. Abbie falls deeper into Vincent's world, bringing Sam with her. Meanwhile, Sean's vigilante justice leads him down a dangerous path.

A confession to Lisa shines a possible new light on Dylan's killer. Abbie has a terrifying experience with some local junkies, and Rob's escalating actions begin to impact on his family. Med starts to suspect Lisa is hiding something from him and begins to investigate by himself.