Paris, 1832. A brutal cholera epidemic is sweeping through the city: the poor are hit the hardest, and panic and rumors flood the streets. Distrust in the authorities’ actions is growing, and the townspeople are increasingly grumbling against the government’s measures. While officials and doctors try to stop the disease, another misfortune strikes the capital: in the Saint-Merri district, bodies with knife wounds are discovered one after another.
The investigation of this strange series of murders is assigned to the Bureau of Dark Affairs, led by Inspector Valantine Vern. By his side are his loyal companion Aglaia and two new recruits: the Deceiver, a former swindler who can expertly lead people by the nose, and Tafiq, an ex-mamluk from Napoleon’s army—an actual giant. But soon everything begins to fall apart: more and more false leads appear, scientists disappear, and Valantine—back at the head of the Sûreté police—closes in on the identity of the Vicar—and on the answer to the question that won’t let him sleep at night: who, in truth, was this criminal serving?