When four postcards are sent anonymously to an advice centre, each with the word "murder" scribbled in a foreign language and the same precise OS map reference, DCI Hennessey and his team visit the sinister location and make a chilling discovery: the body of a professional man who had been reported missing ten years earlier. Who sent the postcards, and why so long after the crime? As Hennessey and his team investigate they find themselves drawn into a puzzling and dangerous investigation.