Readers with a grasp of quantum mechanics would do well to brush up on the Heisenberg Uncertainty Principle before tackling this book. Those without need to know that modern physics believes the act of observing subatomic particles changes their properties and behavior. Thus, it is impossible to accurately understand the true nature of creation at the invisible level because of the unpredictable nature of up and down quarks, bosons, muons and all the rest. With that idea firmly in mind, the reader will have the correct framework to approach China Mieville and his coprophiliac world called New Crobuzon. It's a place somewhere in time (past, present, or future) where everything is in flux. Strange hybrid creatures, possibly the result of an unleashing of the Torque, pursue each other with idiopathic motives that bear only a passing resemblance to those of humans. There are flying snakes, beetles as big as a house, insect-human hybrids, giant carnivorous moths, talking centipedes and all manner of flying, crawling and creeping critters in addition to homo sapiens. In New Crobuzon, it seems the forces of evolution have taken a dark, retrogressive turn.

A Sambo-like obsessive compulsive scientist named Isaac pursues crisis energy, a force he learns about by observing the water sculptures of an inscrutable race of Wyrmen. His lover is Lin, a part human-part grasshopper artist. Together, they feel like outcasts in an already-freakish world where they must hide their affair for fear of public censure. The author begs but does not answer the question of how this menagerie of hybrids and mutants came into existence in the first place. There seems to be no time to address such fundamentals when there is a huge, pulsating pupa in Isaac's laboratory and a depressed garuda who will pay a handsome sum of gold to be outfitted with a reasonable facsimile of the wings he never had. With this all-too-human motive, Isaac ransacks every science book he can find in search of the best way to power these avian prostheses. He settles on crisis energy.

The bugwoman Lin works on a lucrative contract to make a sculpture of a perverse drug dealer named Mr. Motley, by using color excreted from behind her head carapace. When she and Isaac meet, they make furious human-insect love, complete with gentle stroking of her feathery wings. Things get truly nasty when Lin is murdered by Mr. Motley's thugs as events in New Crobuzon go from weird to frightening. The vengeful drug lord, a paranoid Mayor Rudgutter and a militia equipped with 17th Century weapons are joined in an apocalyptic battle between the forces of civilization in New Crobuzon and the forces of death and destruction unleashed in a swarm of carnivorous, man-sized slake moths that soar through the skies looking for humans and any other "blood creatures" to consume.

At this point, the author seems like a necromancer stirring his cauldron of monsters of the id to a frenzied climax and resolution. The author creates a world of half-humans whose drives and motivations are cryptic, which can pose a challenge for the reader. The "willing suspension of disbelief" necessary for a strong connection between author and reader is strained to the breaking point, for example, when Isaac and his companions—fleeing a militia hit squad—encounter a network of "constructs," or robotic forms of intelligent half-life, self-constructed from industrial waste. Happily, this Construct Council sides with Isaac and his friends against the hungry slake moths.

Shallow character development is apparent when Derkhan, one of Isaac's companions, asks him whether he is grieving after the murder of his lover, Lin. Isaac replies that there is hardly time for emotion in the crisis unfolding in New Crobuzon.