Paris is in a fever: the end of the world is expected on November 13, 1899, the Earth is about to collide with a giant comet. And in the Clock Dead End they find a corpse, around which mysterious objects are carefully laid out: stones wrapped in cloth, a plush crocodile, a clepsydra, grains and gravel in a bag. Amateur detectives Victor Legris and Joseph Pinho would like not to interfere, but Commissioner Augustin Valmy unexpectedly asks them for help, because the murdered man is his half-brother.