The Lost Tribe - Wisdom's Quest, #6

Wisdom's Quest presents its grand finale, a time when worlds collide, and humanity stands on the brink of destruction. Sent into hiding by their grandmother, Spirit Wolf and Dancing Butterfly disappear into a parallel world where they learn to work together and conquer their fear and a very real enemy. A sorceress' apprentice joins them on a rollercoaster adventure in time. The world's fate now rests in the hands of three siblings from the ancient future.
The third, Raven Feather, travels with Sahar and Arisnoe, both Atlantean monarchs. A Reptilian invasion threatens their lives, and secrets unravel, exposing a truth they had never expected.