What is the ninth gate?
The ninth gate is the last of nine gates that, when each is correctly passed through, are reputed to conjur or lead to Lucifer. They are described in Novem Portis de Umbrarum Regni (The Nine Gates of the Kingdom of Shadows), a book written in the 1600s by Aristide Torchia. It is said that Torchia co-authored the book with Lucifer himself. Three copies of the book are known to still exist. One copy was acquired by Andrew Telfer (Willy Holt) in Spain and sold to Boris Balkan (Frank Langella) just before Telfer’s death. A second copy is in the collection of Victor Fargas (Jack Taylor) in Portugal, and the third is a part of the collection of Baroness Kessler (Barbara Jefford) in Paris. Balkan has hired rare book detective Dean Corso (Johnny Depp) to authenticate his copy against the two remaining copies, presumably because Balkan has tried to summon Lucifer and found that his book doesn’t get him through the ninth gate.