A visit from Jack's English cousin Brian leads to the unearthing of a devastating family secret, and the Garda sergeant must also deal with a troubled teenager who is the chief suspect in the murder of an elderly recluse. Jack investigates a suspicious fire at a troubled housing development, but his loyalties are tested by the suspicion that an old friend may have been responsible. Meanwhile, Gemma falls out with Brian over his plan to stake a claim to Eithne's land. Jack investigates a car accident involving a local teenager, and suspects the girl of being in an abusive relationship. However, he is unable to focus on the case due to tensions back at home, where he continues to be the subject of Brian's simmering hatred.