As Maggie and her team dig deeper into Callum Reid’s disappearance, they re-interview the Reids and their neighbours, forcing them to reopen old wounds and revisit painful memories, as they find themselves once again under suspicion. When new evidence eliminates the original prime suspect, the holes and inconsistencies in the first investigation begin to emerge and Maggie becomes convinced that Nina Huber, the Reids’ former au-pair, could hold the key. But where is she? And why can no-one find her? Meanwhile Maggie has to process some disturbing news about her own son, Sam, causing increasing tension at home as she struggles to remain focused on the case. The Reids find their coping mechanisms in conflict as Claire's drive to find her child's killer threatens her relationship with their remaining son. Meanwhile, we revisit the events surrounding the night of the barbecue, gradually uncovering the truth about Nina's relationship, the secret lover the Reids’ neighbour Teresa cannot reveal and the fears that haunt young Luke's nightmares. When a trip to Germany leads to a shocking revelation, Maggie is forced to accept that they may have been wrong about the time and even the location of Callum's disappearance. Then Claire makes a disturbing discovery closer to home and Daniel finds himself under growing suspicion. But who is the man who's been watching the Reids' house? And why is he so interested in Maggie?