Accompanying Sherlock Holmes to an ill-omened house in south London, Dr Watson is startled to find a dead man whose face is contorted in a rictus of horror. There is no mark of violence on the body yet a single word is written on the wall in blood. Dr Watson is as baffled as the police, but Holmes soon uncovers a trail of murder and lost love.

Amelia finds it difficult to concentrate on pyramids when her children are in trouble and Cairo teems with enemy agents, including her old nemesis. Can Amelia unmask the Master Criminal and prevent a bloody uprising in Cairo, defend her son against unknown enemies and prevent Emerson from dashing off to fight in the looming war?

At first the interruption to the boredom of Sherlock Holmes seems to have little to do with crime. A governess, whose father vanished ten years ago and who has been receiving money each year, now needs an escort to meet her unknown benefactor. But before the night is over, murder has occurred.

When Holmes and Watson receive a cipher from one of Moriarty's henchmen warning of dark doings at a manor house, they find themselves on the trail of a murderer. Almost immediately, they are on their way to Sussex where they discover a corpse with its head blown to pieces. But all is not as it seems. For the origins of this case lie in America.