S1, E3: High in the hills above Aberystwyth, the body of an unidentified young man is found at the bottom of a lake in a disused quarry near the village of Penwyllt. Tommy James whose business is tractors, lorries and trucks is a very prominent member of the close-knit community as are his close friends local publican Dic Rees and garage owner Gwilym Morgan. Naturally wary of strangers, the trio offer Mathias no obvious leads, but when the body is revealed to be ex-teacher and traveller Michael Reynolds whom everyone in the village seems to have had an affection for, tongues start to loosen. Does ex-convict and loner Wyn Bratton hold the key to uncovering the truth? And will Bratton's lonely life in a caravan in the woods and the obvious parallels that it draws to Mathias' own life threaten the detective's ability to decide whether he's the victim or the killer? Who was Dic Rees' wife Lowri having an affair with? Bratton or Reynolds? Did Dic know about it? And what was the link between the two men and Tommy James' 10 year old son Defi? When Gwilym Morgan's apparent suicide in his own garage turns out to be murder and Michael Reynolds is found to have drowned not in the quarry lake but somewhere much closer to home, who can Mathias really trust? In a community that lives by its own rules, what is the price of silence if brother turns against brother and the innocent pay the price? Mathias for one knows the answer.