DAC Sumpter asks Commander Clare Blake to take charge of the investigation when Joan Hall, mother of former DS Brian Hall, is found beaten to death in her own home, and Brian is accused of the murder. When his prints are found on the murder weapon and his blood also found at the scene, Clare believes it to be an open-and-shut case, but DCI James refuses to accept that his former colleague could ever be responsible for such a crime. Meanwhile, James' wife Zoe goes into labour, but an argument with a fellow-to-be proves to be the action which begins a chain of terrifying events, when his new baby is abducted from the maternity ward.

Clare begins to feel the pressure of two high-profile yet deeply personal cases coinciding. The investigation to the abduction of James' baby leads to the mothers at Zoe's maternity classes, while Brian Hall still has no recollection of what happened on the night of his mother's murder. As he becomes resigned to the fact that he may have killed her, an incident in prison spurs him to remember a crucial development. But can he persuade an already deflated James that he is telling the truth? A supervised trip to the murder scene convinces Hall that there was someone else in the room when he discovered his mother's body.

Acting on instinct, Clare digs deeper only to find that the truth is more shocking than any of them could have imagined. The investigation into James' missing baby leads Clare to Fiona George, a fellow mother at Zoe's maternity classes. However, her judgement proves to be her downfall, as she commits a desperate act in a bid to reunite James with his baby. As the consequences of Clare's actions bite, rookie DC Marion Randall's hunch leads her to the real abductor. Clare is tested both personally and professionally - but has she gone too far this time?