The body of Leo Hawkins is found in a Devon holiday cottage, the cause of death carbon monoxide poisoning. Was this a tragic accident or something more sinister? CSI Ally Dymond will follow the evidence wherever it leads.

Leo’s wife gives an account of his final hours, but something isn’t adding up. Graffiti left by an anti-tourist group is discovered nearby. The only consistent thread in the investigation is that no one is telling the truth.

When a second body turns up, Ally and the murder team must examine everything they thought they knew, untangling a web of suspects to get to the truth. But can they catch the killer before they strike again?