Maybe it's because I read The Bones of Paris first (it's the second Harris Stuyvesant book). I don't know; I just preferred the second book.
In this outing, FBI agent Harris Stuyvesant is in England chasing after an anarchist bomber whose identity he is sure he knows. With no support from J. Edgar Hoover, Stuyvesant is trying to work his way through England's intelligence community. He's eventually referred to Major Aldous Carstairs ... who sics him on Captain Bennett Grey, a WWI veteran whose PTSD has taken the form of psychokenesis. He can tell whether someone is lying, and to whom an object has belonged.
He also has a lovely sister, Susan, who is friends with the suspected bomber's mistress.
There are all manner of challenges to deal with, such as the General Strike (it's 1921, and the miners and owners are at odds with each other), class politics and more.
I enjoyed the story, to be sure ... and was more than a little surprised when the plot reached its climax (it is hard to surprise me with these sorts of books, to be honest). I just liked the second one a bit more.