Dean Corso (Johnny Depp) is a New York City rare-book dealer motivated solely by financial gain. Wealthy book collector Boris Balkan (Frank Langella) hires Corso to authenticate his recently acquired copy of the seventeenth-century author Aristide Torchia’s book The Nine Gates of the Kingdom of Shadows, reputedly a version of a book whose author was the devil himself. The book contains nine engravings that, when correctly interpreted and the legends properly spoken, will raise the Devil. Since two other copies exist, Balkan suspects that the book might be a forgery, and asks Corso to travel to Europe determine whether his or any of the other two are genuine and, if so, to acquire them for Balkan, at any cost or by any means.
Balkan’s copy of The Nine Gates had previously belonged to bibliophile Andrew Telfer, who committed suicide soon after selling the book to Balkan. Moreover, Telfer’s widow, Liana (Lena Olin), wants the book back, as Telfer originally bought the book for her. Liana seduces Corso but fails to re-acquire her book. Meanwhile, Corso’s business partner and rare-book shop owner, Bernie (James Russo), whom Corso had asked to hide the book, is murdered and his corpse disposed to reflect one of the engravings in The Nine Gates, which, as in the image of the The Hanged Man Tarot card, shows a man hanged by one foot upside down.
Corso travels to Toledo, Spain, to talk with the Ceniza brothers (José López Rodero), twin-brother book restorers, who point out to him three of the book’s engravings signed “LCF”, which, with their prompting, Corso understands means that Lucifer himself designed and cut them. Corso next goes by train to Sintra, Portugal, and visits Victor Fargas (Jack Taylor), in a mysterious house (the main house of Quinta da Regaleira), whose copy of The Nine Gates Corso compares with Balkan’s. To his surprise, he discovers that the signature “LCF” is, in the Fargas copy, found in three different engravings, which vary in detail from their counterparts in the Balkan copy. The next morning, a mysterious young woman (Emmanuelle Seigner) who has crossed paths with Corso since Balkan summoned him for this assignment awakens Corso and leads him back to Fargas’s house to find the old man murdered and the engravings ripped out of his copy of The Nine Gates. Later, the unnamed woman displays supernatural abilities in rescuing Corso from Liana’s bodyguard (Tony Amoni).
In Paris, Corso visits examines the Baroness Kessler (Barbara Jefford), owner of the third copy of The Nine Gates, The Baroness initially refuses any contact with Corso once she realizes who his employer is, but Corso returns and intrigues Kessler — a lifelong devotee of the study of the book — with evidence that the engravings differ between the copies. Having gained access to Kessler’s copy, he records three further differences; later, Kessler is killed, and the engravings from her book also ripped out. Now believing that each copy of The Nine Gates is genuine, Corso suspects that the secret to opening the nine gates is a combination of the ‘LCF’ versions of each of the nine engravings, distributed across all three copies of the book. Liana steals Balkan’s copy from Corso’s hotel room; he follows her to a mansion, and witnesses her using it in leading a Satanist ceremony. Suddenly, Balkan interrupts the ceremony, kills Liana, takes the engraving pages, and his own, intact, copy, and flees.
Concluding that Balkan likely killed Fargas and the Baroness, Corso pursues Balkan to a remote keep (which was depicted in a postcard Corso found in Kessler’s copy), and finds Balkan preparing to open the nine gates. After a struggle, during which Corso wields and then drops a pistol he took during an earlier confrontation, Balkan manages to trap Corso in a hole in the floor, thus immobilizing him and allowing Balkan to perform his summoning ritual unmolested (but with Corso as a ‘witness’.) Balkan recites a series of phrases related to each of the nine engravings, then douses the floor and himself with gasoline and sets it alight, believing himself immune to the flames. Balkan’s invocation, however, appears to fail, and Balkan begins screaming in agony as his body starts to burn. Corso frees himself and, with no alternative, puts Balkan out of his agony with a shot and escapes the fire. Outside the building, Corso encounters the mysterious unnamed woman and (possibly without any say in the matter) has sexual intercourse with her by the light of the flames. Later, she tells him that Balkan failed because the ninth engraving Balkan had used was a forgery. Corso, following her directions, returns to the Ceniza brothers’ shop. On arriving, he finds the store gone and the last piece of furniture being removed, from the top of which falls the final, authentic, engraving, which includes a likeness of the mystery girl. With the last engraving in hand, Corso returns to the castle it depicts and crosses the threshold of the Ninth Gate.
Second audio track : Director’s commentary.