The Amethyst — William L. Stuart

In Celahir, the magical land where the Light Elves and the Dark Elves live, the four gemstones of the Elven Bow have been stolen by the Dark Elves. Without those gemstones, the barrier between the human world and Celahir is deteriorating and the balance between good and evil in both worlds is tipping toward evil. The first of the gemstones, the Carnelian, was recovered by Aidan, Maggie, Nana, and Beebop with help from their Light Elf friends during their first trip to Celahir. Now, the stakes are even higher when the elves return to the human world to ask for help recovering the second gemstone, the Amethyst, and the humans discover that Mike â€" Aidan and Maggie's father â€" has been kidnapped by the evil elf Naesse! The humans, accompanied by Aidan and Maggie's mother, Laura, return to Celahir to rescue Mike and recover the Amethyst. All they have to do is defeat the giant that guards the gemstone…