1752, the Liverpool Merchant sets sail from Merseyside. A slaver, she is bound for Africa to buy men and transport them in chains across the Atlantic. But aboard ship disease thrives in the cramped hold, killing men and eating into profit.
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.