Summary (located on the back of the book): Lucas Corso is a book detective, a mercenary hired to hunt down rare editions for wealthy and unscrupulous clients. When a well-known bibliophile is found hanged, leaving behind part of the original manuscript of Alexandre Dumas' The Three Muskateers, Corso is brought in to authenticate the fragment. He is soon drawn into a swirling plot involving devil worship, occult practices, and swashbucking derring-do among a cast of characters bearing a suspicious resemblance to those of Dumas' masterpiece.
Corso is given The Book of the Nine Doors that has nine woodcuts supposedly originally made by the devil and it's supposed to show you how to summon the devil. There are three known copies, but only one is the original and Corso is sent to compare the three copies.
I really enjoyed the book, although sometimes it was a little confusing. My confusion was quickly remedied, however. It had just the right amount of conspiracy and suspense, as well as a mysterious club and characters dressed as if they were from The Three Muskateers. I wouldn't really suggest reading it unless you hold at least a little interest in Dumas and his book The Three Muskateers. The ending was fantastic and it didn't finish how I thought it would. It started slow, but once it sucked me in I really couldn't put it down until I fell asleep at three in the morning over its pages. I would recommend buying it.