DCI Cadi John has to release Karl Lewis because of a lack of evidence. Mia, Connor and Lee cause trouble for Hefin, Beca and Sion at the petrol station.
When the body of an old man is discovered in a house on the outskirts of Blaenau Ffestiniog, D.C.I. Cadi John and D.S. Owen Vaughan are called upon to lead the investigation.