SPOILER ALERT!!
Talking to Conrad at Bakyre started this quest. Conrad indicated that a pirate called Redbeard stole the book. The boat sunk and if there are any survivors they must be at "Buccanrer's Den".
Buccanrer's Den
Talked to Orlando about Redbeard reveals that the ship sucked into the underworld through a giant Whirlpool. And points me to Dante. The ship 'Sunderland'. Asking about the book reveals that Redbeard stole it from the Library. Asking Orlando about the book reveals the same - stole from the library.
The Underworld
Using a raft I've managed to enter the Underworldjust to fight a Darke.
So - get invisibility stuff to bypass him! I've barely scratched him at lvl-33.
The place is crawling with Drakes, so, I belive that soloing this place is very hard!! Bring your gang or be lvl 50+ or so.
Tried again at level 39, with lots of invisibility stuff and I was able to hide myself until I got to the ship.
In the ship there is Redneck spirit - killed it and the book is mine, teleported back to safety.
*** The End ***