The strangled body of teenager Diane Thornburn is found buried in the salt store in a Cheshire village. Diane's best friend, Margie Poole, knows more than she is prepared to tell. Chief inspector Woodend is drafted in from London to investigate - his inquiry turns up the death of another young girl a generation before, and the similarities in the two cases begin to look like more than just a coincidence. Is there a serial killer on the loose and, if so, where and when will he strike next?