In this macabre and intricate fantasy, a quarantined city is under a threat that its citizens cannot escape from since there is no where to run and nowhere to hide.

“Dizzying and bright, a masterful novel that sits somewhere in the space between Frances Hardinge and Philip Pullman.”—Tor

“Epic . . . Recommended for fans of Sabaa Tahir’s An Ember in the Ashes and Leigh Bardugo’s Six of Crows.”—School Library Journal

In a walled city of mile-high iron guild towers, many things are common knowledge: No book in any of the city’s libraries reveals its place on a calendar or a map. No living beasts can be found within the city’s walls. And no good comes to the guilder or foundling who strays too far from their labors. Even on the tower rooftops, where Errol Thebes and the rest of the city’s teenagers pass a few short years under an open sky, no one truly believes anything uncommon is possible within the city walls.

But one guildmaster has broken tradition to protect her child, and now the whole city faces an uncommon threat: a pair of black iron spikes that have the power of both sword and needle on the rib cages of men has gone missing, but the deadly mayhem they cause rises everywhere. If the spikes are not found and contained, no wall will be high enough to protect the city—or the world beyond it.

And Errol Thebes? He’s not dead and he’s certainly not safe.