Tillie Pembroke’s sister lies dead, her body drained of blood and with two puncture wounds on her neck. Bram Stoker’s new novel, Dracula, has just been published, and Tillie’s imagination leaps to the impossible: the murderer is a vampire. But it can’t be—can it?A ravenous reader and researcher, Tillie has something of an addiction to truth, and she won’t rest until she unravels the mystery of her sister’s death. Unfortunately, Tillie’s addicted to more than just truth; to ease the pain from a recent injury, she’s taking more and more laudanum…and some in her immediate circle are happy to keep her well supplied.Tillie can’t bring herself to believe vampires exist. But with the hysteria surrounding her sister’s death, the continued vampiric slayings, and the opium swirling through her body, it’s becoming increasingly difficult for a girl who relies on facts and figures to know what’s real—or whether she can trust those closest to her.

    There must be a victim. A suspect. A detective. The rest is just shuffling the sequence. Expanding the permutations. Grant McAllister, a professor of mathematics, once sat down and worked them all out – calculating the different orders and possibilities of a mystery into seven perfect detective stories he quietly published. But that was thirty years ago. Now Grant lives in seclusion on a remote Mediterranean island, counting the rest of his days.Until Julia Hart, a sharp, ambitious editor knocks on his door. Julia wishes to republish his book, and together they must revisit those old stories: an author hiding from his past, and an editor, keen to understand it.But there are things in the stories that don’t add up. Inconsistencies left by Grant that a sharp-eyed editor begins to suspect are more than mistakes. They may be clues, and Julia finds herself with a mystery of her own to solve.