It is 1918, and London is gathering in its dead. For undertaker Henry Speake, laying to rest the bodies of those sent home from the Front has become a familiar duty. But what he is seeing now, as influenza claims its victims, is something different.
The first message sent to Tom Thorne's phone was just a picture - the blurred image of a man's face, but Thorne had seen enough dead bodies to know that the man was no longer alive. But who was he? Who sent the photograph? And why? While the technical experts attempt to trace the sender, Thorne searches the bulletins for a reported death that matches the photograph. Then another picture arrives.