From Bangor, overlooking the churning waters of the Menai Straits, to the abandoned quarries of Llanberis, this is a landscape DI Cadi John knows well. A world she never expected to return to. Drawn back for personal reasons - the faltering health of her beloved father - Cadi finds herself policing the precinct and people of her youth. It is a job she enjoys. However, when the body of a local woman is found in a remote river, Cadi's world - and the world of those around her - is changed forever. The investigation leads to the reopening of a cold case and identifies a possible miscarriage of justice. Leading actress Sian Reese-Williams commented that the series was more of a "personal drama" than a crime series, because of the multiple human stories involved, including those of the victims, the families of the victims, and the criminal protagonist.