Beneath the towering bleached ribs of a dead, ancient beast lies New Crobuzon, a squalid city where humans, Re-mades, and arcane races live in perpetual fear of Parliament and its brutal militia. In New Crobuzon, the unsavory deal is stranger to none - not even to Isaac, a brilliant scientist with a penchant for Crisis Theory. Isaac has spent a lifetime quietly carrying out his unique research. But when a half-bird, half-human creature known as the Garuda comes to him from afar, Isaac is faced with challenges he has never before fathomed. While Isaac s experiments for the Garuda turn into an obsession, one of his lab specimens demands attention - a brilliantly colored caterpillar that feeds on nothing but a hallucinatory drug and grows larger - and more consuming - by the day. What finally emerges from the silken cocoon will permeate every fiber of New Crobuzon - and not even the Ambassador of Hell will challenge the malignant terror it invokes.