Chicago's magnificent White City will soon be fading into memory. As the grand Exposition of 1893 reaches its final day, the metropolis is rocked by the public assassination of its popular mayor. In the chaos that ensues, another murder — the savage slaughter of a Pinkerton agent posing as a prostitute in a seedy slum alleyway — goes virtually unnoticed . . . except by police inspector Alastair Ransom.

An avenging angel haunted by the ghosts and mistakes of his past, Ransom called the slain detective, Nell Hartigan, "friend" — and his unorthodox inquiries into her murder are pointing him toward a fiend who's targeting the city's most unremarkable and disposable citizens. But in a great urban slaughterhouse, where foul corruption festers in every dark corner, Ransom will find himself accused of the one crime he did not commit . . . and facing the final judgment of the hangman's noose.