Ex-cop Jack Taylor is approached by a grieving father who wants to get revenge on those responsible for his daughter's murder, in this 12th outing (after Green Hell). Jack agrees to help but is soon derailed by the appearance of Emily, a chameleon-like young woman who is by turns passionate, clever, and utterly homicidal. She is ready to use any sort of coercion to get Jack to conspire with her against the serial killer nicknamed "the Grammarian"—a Cambridge graduate who becomes murderous over poor usage of the English language—but her most destructive obsession just might be Jack himself.