The chance discovery of a gravestone, seemingly out of place among the ancient, and weathered monuments of a London cemetery, begins a simple quest to pass the time for the retired army officer, turned detective. Bartholomew Bigelow Butterworth's gravestone has strange epitaph that reads: Brother, Betrothed, Bastard. On the side is symbol all too familiar to him, a representation of a horse brand used during the 2nd South African War. Who added that symbol, and why? It was two of a series of marks branded on British war-horses. The arrow pointing down said the horse was sick or injured, and had been sold. Beside it was a second brand pointing to the front. That one would have been put there by the Boer who found the animal and restored it to health to ride against the British.

His casual inquiry turns deadly serious when he and his partner stumble on a closed case that Scotland Yard had attributed to suicide. But, after reviewing the evidence, they are convinced it was actually murder. As the dawn of the Great War in Europe approaches the dead man's sister arrives at his doorstep and the mystery grows deeper. She has come to ask him to officially investigate her brother's demise, but she has not come alone. Nothing is entirely as it appears. Wherever she goes it seems that spies, espionage, and death will follow. It is only days before the Great War begins and the armies are preparing for battle. James Horn and Anthony Hillman must give up the search for the killer and return to army intelligence. Soon they realize that this was not a case of domestic homicide, but a case of Germany espionage against Britain and the agent leading the way Was a traitor thought to have died in South Africa.

He returns to England and murders his best friend Arthur Shaw who was also thought to have died in the war. He stages the murder in such a way that everyone thinks it was he who had committed suicide. then he waits for eighteen months before beginning his acts of serial murder.

Though he is working for the Germans, all his attacks are all aimed at exacting revenge on the people he was closest to before he went to war in Africa, those he feels have wronged him in some way. His main targets are his (supposed twin) sister Jennifer her mother Henrietta who is in fact his step mother and his former fiance Cynthia Shaw, his best friend's sister. all of them will die if he is left to continue. James figures out what he is up to and catches up to him at Jennifer's country home in Scotland. There he finds the Ghost, Bart Butterworth holding Jennifer and Henrietta hostage and preparing to make off with them to the coast. Bart escapes with his prisoners through a secret passage and races to meet his ship to freedom. James speeds after him and catches his once again on the beach with Bart's ship in sight. James brings down Bart with a shot to the head and a small British war ship sinks the German vessel ending that early German invasion of the British Isles of World War One. The End.