PROLOGUE London, April 1878. The demon exploded in a shower of ichor and guts. William Herondale jerked back the dagger he was holding, but it was too late. The viscous acid of the demon’s blood had already begun to eat away at the shining blade. He swore and tossed the weapon aside; it landed in a filthy puddle and commenced smoldering like a doused match. The demon itself, of course, had vanished—dispatched back to whatever hellish world it had come from, though not without leaving a mess behind. “Jem!” Will called, turning around. “Where are you? Did you see that? Killed it with one blow! Not bad, eh?” But there was no answer to Will’s shout; his hunting partner had been standing behind him in the damp and crooked street a few moments before, guarding his back, Will was positive, but now Will was alone in the shadows. He frowned in annoyance—it was much less fun showing off without Jem to show off to. He glanced behind him, to where the street narrowed into a passage that gave onto the black, heaving water of the Thames in the distance. Through the gap Will could see the dark outlines of docked ships, a forest of masts like a leafless orchard. No Jem there; perhaps he had gone back to Narrow Street in search of better illumination. With a shrug Will headed back the way