The third episode opens with a flashback showing Finn, Toby, Kieran, Verity, and Brian all on a boat together preparing to go diving. Finn tells Kieran that he and Toby are considering adding a tour of the caves to their boat trip business and asks Kieran to scout it out. Kieran agrees but promises Brian and Verity he will go at low tide because it is dangerous.

Brian is arrested for murder in Episode 3, with suspicion that he may have killed Bronte. However, the question of whether he actually committed the murder remains uncertain at this point in the story.

In Episode 3, it is revealed that Sean was with Bronte at the beach and was involved in her death after a confrontation. Sean killed Bronte to cover up his involvement in Gabby's death and tried to frame Brian for the murders. Verity discovers the truth from Sean's father and alerts the police, leading to Sean's arrest. Kieran is rescued from the cave and cared for by paramedics.

Kieran begins to feel less like a visitor and more like a threat to those who want the past to remain buried. The episode shows tension among former friends, strained family ties, and a community clinging to a version of events that minimizes pain. The characters circle each other with withheld truths and emotional weight deepening.

In the present day of Episode 3, Kieran and Verity paint over graffiti on the garage. Verity notices that the garage is unlocked despite Kieran's promise that he had locked it the previous day, suggesting possible tampering or intrusion.