The Ninth Gate
From IMDB:
In New York, the money-driven dealer Dean Corso is a rare-books expert and partner of Bernie, who owns a bookstore. He is contacted by the renowned collector of books about the devil Boris Balkan, who has just acquired the rare The Nine Gates of the Kingdom of Shadows from the collector Andrew Telfer, to verify whether his book is authentic or a forgery. Balkan explains that the book was written by the writer Aristide Torchia, in 1666, with Lucifer and he was burned at the stake with his entire work. There are only three exemplars of The Nine Gates and in accordance with the legend, its nine engravings form a riddle to conjure the devil.
Link to the rest at IMDB