From the back of the book:
"The Feadiel clan's Tree of Life is dying. As the bravest and strongest elves in the clan, you must undertake the challenge of the elders: seek out the source of the disease and destroy it.
If you fail, the Tree of Life will surely perish, and all your family with it. The quest is great and you may die on the journey, never to find the cause of the disease. The journey will take you to the deepest part of ancient Selinar, Elvenhome, to find the guarded grave of the first Treekeeper.
Delay no longer! The Tree of Life grows weaker, day by day..."