Édouard, a collector and seller of ancient books, owns a precious notebook that dates back to the 17th century, which is said to have been kept by a certain Melchior Soubeyran. When he entrusts it to the narrator, who plunges into it, the latter finds himself rushed to Moscow in 1689 to the bedside of Jean-Baptiste Tavernier, dying before the eyes of his young apprentice. Past his eighties, the Protestant author of Six Voyages to Turkey, Persia and India, who was Louis XIV's supplier of exceptional diamonds, was forced to take the road to the East again. This seventh departure is a consequence of the persecutions unleashed by the revocation of the Edict of Nantes, but also of the shenanigans of his flamboyant brother-in-law, supposedly a prince of Persian blood and certainly a swindler of the most beautiful water.

While his master is delirious and threatens ghosts that only he can see, the young Melchior sinks into his notebook like a hunted animal down in too soft a soil. The fever contaminates the pages, in the Moscow night, and the narrator, caught in his turn, will not escape it…