Order has collapsed in Deepgate. The chained city is now in ruins; the Deadsands beyond are full of fleeing refugees. The Spine militia, unable to come to terms with the loss of their church, are trying to halt the exodus with brutal force.
Driven away by the mob, Rachel Hael leads Dill along a very dangerous route through the wastelands, but what should have been a straightforward flight to Sandport becomes a desperate march for survival after the angel is captured and mutilated. Yet Dill has been crippled by more than the loss of his wings, for memories of hell haunt him. Rachel just wants to keep her friends alive, but the offspring of the dread goddess Ayen have other ideas, the death of the underworld god Ulcis having not gone unnoticed by his six siblings. Cospinol, the god of brine and fog, is coming for his brother's murderers, and he's bringing his own version of hell with him. Wreathed in fog, Cospinol's foul skyship has already reached Sandport.
Cog Island will now become the focus for a clash of powers: of men and gods and archons and slaves all forced into desperate alliances, a battle in which the outcome will be decided not by force, but by sacrifice. Whoever wins, it's bad news for everyone except Iril, god of death. For in the end there's going to be a lot of blood.