There is a book called The War of Gods and Giants on one of desks in the museum. Find it before the Thieves do.
Thieves
Target: Museum
As soon as you found the book, you were attacked! Destroy all the attackers!
Speak with Pantheon
Target: Pantheon
You have defeated all Thieves. You have to go back to Pantheon and inform him of what happened here. Let's tell Museum Keeper Toyron that you are going back to the museum lobby.
The War of Gods and Giants
Target: Museum
There is a book called The War of Gods and Giants on one of desks in the museum. Find it before the Thieves do.
Thieves
Target: Museum
Those suspicious people turned out to be thieves that appeared at the very moment when you find the book. Let's defeat all Thieves.
Speak with Pantheon
Target: Pantheon
You have defeated all Thieves. You have to go back to Pantheon and inform him of what happened here. Let's tell Museum Keeper Toyron that you are going back to the museum lobby.
Intruder Who Wants the Book of Giants Intruder Who Wants the Book of Giants
Talk to Pantheon in Talking Island Village. The book The War of Gods and Giants is somewhere in the museum, and you need to find it. Once you agree to help, he'll move you to the inner part of the museum.
Go up to the tables in the four corners of the room and look for The War of Gods and Giants. As soon as you find it, two thieves Thief (lv. 65) attack you, and the museum guard Toyron rushes to help you (well, "rushes"... he'll run in circles and go on about needing to hit them with skills). Normal attacks won't hurt them; you can only kill them with skills, and the faster you do it the better, since these guys hit really hard.
Talk to Museum KeeperToyron to have him move you back to Pantheon.