Another movie that swipes the whole idea behind the "Cthulhu" stories. Or behind the Cthulhu role-playing game. Take your pick.
I only half-watched this movie, but, from what I saw, it wasn't too bad. The plot has Johnny Depp tracking down three copies of a Satanic text, some or all of which might be forgeries. It turns out that ALL of the copies are forgeries too some degree-- but that parts of the REAL Satanic text -- coauthored by the Prince of Darkness himself -- are included in each of the three forgeries; find the real parts of each and put them together and... well, nothing good, one imagines.
I really liked the book-detective-work in this film. Without explaining the details, I'll just say that it's creepy and cool watching Depp figure out which elements of the texts are the real Satanic manifesto.