Summoned to the riverside by the desperate, scribbled note of an old friend, Jem Flockhart and Will Quartermain find themselves onboard the seamen's floating hospital, an old hulk known only as The Blood, where prejudice, ambition, and murder seethe beneath a veneer of medical respectability.

On shore, a young woman, a known prostitute, is found drowned in a derelict boatyard. A man leaps to his death into the Thames, driven mad by poison and fear. The events are linked--but how? Courting danger in the opium dens and brothels of the waterfront, certain that The Blood lies at the heart of the puzzle, Jem and Will embark on a quest to uncover the truth. In a hunt that takes them from the dissecting tables of a private anatomy school to the squalor of the dock-side mortuary, they find themselves involved in a dark and terrible mystery.