Hidden

The life of DI Cadi John and the lives of those around her are forever changed by the discovery of the body of a young woman, Mali Pryce, in a river. Mali has been missing since 2011 and the police question where she has been held for all this time. Will the person responsible for Mali's death strike again? The pressure is on for the North Wales police force to find some answers quickly.

The police can't ignore the similarities between the case of missing girl, Llinos Evans, who has never been found, and the discovery of Mali Pryce. Could this be the work of a serial offender? DI Cadi John and DS Owen Vaughan pay Sara Dean, an old school friend of Mali's, a visit and they learn about how troubled Mali's past was. Local drug dealer Ieuan Rhys accuses the police of not caring at all when Mali went missing, they didn't want to help then, so why should he help them now?

The police investigation enters a new phase when DI Cadi John and DS Owen Vaughan are called to the scene of a potential kidnapping in the middle of the night. Their concerns that a serial kidnapper is on the loose are confirmed.

Dylan Harris holds Megan captive in a locked subterranean room in a strange compound in which he lives with his mother and young daughter. When PC Mari James and PC Ryan Davies pay a routine visit to ask Dylan if he knows anything about Mali Pryce, Dylan manages to convince PC Davies that he knows nothing. However, PC James's suspicions are aroused by this peculiar man who lives in the middle of nowhere.

The police realise the horror of Mali Pryce's circumstances as the post-mortem results come in: she was brutalised, and the urgency of the investigation increases. Meanwhile, DI Cadi John sees that her father's health is rapidly failing.

The investigation leads DI Cadi John to Gladwell Prison where Endaf Elwy has spent over a decade locked away for the murder of his young niece. On seeing Endaf, Cadi's suspicion that an innocent man has been wrongly accused is confirmed.