DCI Boyd's first task as head of the new Cold Case Squad is to find the killer of a schoolgirl murdered five years ago. But as they begin work, they inadvertently inspire the killer to strike again. And, unbeknown to Boyd and his team, the murderer has a hidden agenda - to take revenge.

When Detective Superintendent Boyd encounters a woman unable to accept the explanation of her father's death in a terrible car crash, he takes on the case.