The Cthulhu Encryption — Brian Stableford

The Shoggoths attack: "They had been so horrible before that I dare not say that they were any MORE horrible when they came again.... They were still unspeakable, still unthinkable--but whether I could speak or think of them or not, they were HERE." Auguste Dupin is one of the few persons who can identify the rare Cthulhu Encryption etched in the flesh of a dying woman. The Comte de Saint-Germain owns a companion cryptogram that he believes is the key to finding a fabulous treasure buried by the pirate Levasseur. Harassed by Shoggoths and tracked by Saint-Germain, Dupin must find the key to the complex puzzle. Can the might of Cthulhu be held at bay? And even if he finds an answer, can he and his friends escape with their lives? A riveting horror novel.