The Key to the Secret Book

The Key to the Secret Book is a Mu Lung + Nihal Desert quest started by Phyllia.

Part of Dr. De Lang, the Missing Alchemist: see every quest in order.

Requirements

Offer: Have you gone to the underground study? It must have been really messy down there, since no one has visited the area in such a long time... did you find anything interesting?
A book with a hole in the middle? I knew there were numerous books downstairs, but I've never opened them before, so I had no clue something like that would be inside the book. Maybe that book might have a clue or two on Dr. De Lang. I wonder what, if anything, will fit in that hole, though...
Silver Pendant...? If Dr. De Lang really made Silver Pendant, then that makes perfect sense... and yet, it's the only item that De Lang left with me......if we need to find out more about De Lang and his whereabouts, then that is our only clue. I'll give you Silver Pendant, so please find out more about Dr. De Lang for me.
In progress: I already gave you Silver Pendant... Haven't you gone back to the underground study and place it in that strange book?
Completion: (After carefully opening the book, I placed Silver Pendant in the hole. The fact that the rose engravings on the pendant fits right in confirms that this is the key to the book.)