When Eric Ward and Sharon Owen defend suspected serial killer Raymond Conroy, they win an acquittal on a technicality, thus incurring the wrath of CI Charlie Spate. Ward has no desire to act further for Conroy when the man decides to remain in the northeast. Instead, he concentrates on issues arising from Sharon's family trust although he is continually harassed by a journalist who seeks to interview Conroy. When Conroy disappears and the Zodiac Killer strikes again, Ward finds himself involved once more alongside CI Spate, who is under pressure for his apparent incompetence in tracking Conroy. Complications arise from mysterious dealings in Scotland in the 1970s, but it is only during a murderous climax in a remote Northumberland farmhouse that the truth finally emerges in the hunt for the Zodiac Killer.