Central to Kostova's story is a name that actually exists in the pages of history -- Dracula.
A national folk hero in Romania known as Vlad Tepes, the 15th-century ruler who successfully staved off invasion by the Turkish Empire, called himself Vlad Dracula.
According to scholar Elizabeth Miller, Dracula was a nickname derived from his father, who went by Dracul, the Romanian word for dragon.
"Dracula was sort of like the son, the little dragon or the son of the dragon," said Miller.
Vlad Dracula, who led his army in a famous stand at the Poenari Fortress against the invading Turks, was known as both a great warrior and a brutal tyrant, Miller said.
He called himself Vlad Dracula, but he is known by Romanians and Medieval historians as Vlad Tepes -- Vlad the Impaler in English for his preferred method of execution.
Vlad Dracula was known to have impaled Turkish prisoners as a tool of psychological warfare against the threatening Turk forces. "Vlad had to impale Turkish prisoners in what was labeled a forest of the impaled. The response was, 'We don't want anything to do with this guy. Let's turn around and go home,' " said Miller.
Historical opinion on Vlad also was influenced by a rare German pamphlet. One of the few remaining copies in the world is at the Rosenbach Museum and Library. Barsanti said the pamphlet lists atrocities committed by Vlad, including accounts of Vlad impaling visiting monks and other visitors.
Vlad's legend got even darker and more mysterious after he died. It is said he was martyred at the hands of Turkish enemies who beheaded him.
"After he was killed, the story goes, his head was taken back to Constantinople as a trophy for the Sultan and Vlad's headless body was buried at a monastery in Snagov, which is about 25 miles from Bucharest," Miller said.
But four centuries later when the monastery site on Snagov Island was excavated, the grave was empty and a historical mystery began. Where was Vlad Dracula's body?
Kostova's novel follows a contemporary woman on a trail through history. In that plot the grave at the monastery is empty because Vlad Dracula is still alive.
"There are really two Draculas," Kostova said. "One of them of course is Vlad the Third of Wallachia, this historical figure who had been named Dracula. And the other is the creation of an author, Bram Stoker's Dracula. In my book I've made a jump to fuse the two."
The connection between the two has been made before in a work of nonfiction. In their groundbreaking 1972 work "In Search of Dracula: The History of Dracula and Vampires," Radu Florescu and Raymond T. McNally, Boston College historians, traced the history of Vlad the Impaler and suggested that he was the prototype for Stoker's Dracula.
"The merit of that book is that it did bring into Dracula's scholarship a whole new group of people," said Miller.
Stoker's personal notes held at the Rosenbach Library suggest that the author read about the 15th-century ruler Vlad Dracula in a book published in 1820 by William Wilkinson called "Account of the Principalities of Wallachia and Moldavia." In Wilkinson's book it stated that the name Dracula also meant devil.
Stoker seemed to like this name. His notes show that he crossed out another name he'd been using, "Count Wampyr," and wrote in Dracula.