Aboard a vast seafaring vessel, a band of prisoners and slaves, their bodies remade into grotesque biological oddities, is being transported to the fledgling colony of New Crobuzon. But the journey is not theirs alone. They are joined by a handful of travellers, each with a reason for fleeing the city. Among them is Bellis Coldwine, a renowned linguist whose services as an interpreter grant her passage - and escape from horrific punishment. For she is linked to Isaac Dan der Grimnebulin, the brilliant renegade scientist who has unwittingly unleashed a nightmare upon New Crobuzon.

When the ship is besieged by pirates, the surviving passengers are brought to Armada, a city constructed from the hulls of stolen ships, a floating, landless mass ruled by the bizarre duality called the Lovers. And no one may ever leave.

Lonely and embittered in her captivity, Bellis knows that to show dissent is a death sentence. Instead, she must furtively seek information about Armada’s agenda. The answer lies in the dark, amorphous shapes that float undetected miles below the waters - terrifying entities with a singular, chilling mission …