When the body of a young woman is found in a local river, it becomes obvious that sinister secrets lie within the stunning North Wales scenery. Cadi's world - and the world around her - is changed forever.

Cadi and Owen investigate a possible link to another girl who disappeared. Megan hides her difficulties from friends and family. Dylan takes an interest in Lowri.

Marc is questioned by the police. Cadi avoids talking to her father or sisters about his condition. Megan tries to take catch up with her schoolwork but Ffion notices something's wrong. Sara visits Lea, Mali's sister.

Dylan and Iona clash regarding Megan. Mari and Ryan continue the questioning procedure, but Mari deviates from protocol.

Cadi and Owen discover a possible connection to an old case, which Cadi's father investigated. Lowri tries to return to her normal routine.

Cadi questions Endaf in prison about the murder he was convicted for. Owen reviews the older case files and receives a new missing persons report. Iona visits Megan.

Cadi and Owen search for new evidence in Endaf's case, which was originally headed by Cadi's father Huw. Dylan works with Matthew at his yard. Megan tries connecting with Nia.

With Dylan on the run, the investigating team attempt to put together an exact timeline of his actions and find further evidence.