Britain is now in an arms race with other European powers. When the mutilated corpse of a young servant, Kitty Ryder, shows up, Thomas Pitt is called in, since Kitty’s employer was the rich and powerful Dudley Kynaston. It looks as if he was being blackmailed into giving naval secrets to a foreign power. When other murders occur, and Pitt struggles with the investigation, his wife Charlotte and her sister Emily start their own enquiries, as they used to together in previous books. Emily’s husband has had a promotion in the government and is now working with Kynaston. Together they can reach parts of society and gain information that event Pitt can’t. Europe might ignite into a world war, if they can’t.