Horizon - Jenn Reese

In this third and final adventure in the Above World series, Aluna and her friends finally face their most terrifying enemy, Karl Strand.

Aluna and Hoku, Kampii from the City of Shifting Tides, and their friends, Equian Dash and winged Aviar Calli, are determined to stop a war. The maniacal ex-scientist Karl Strand is planning to conquer the world with his enormous army of tech-enhanced soldiers . . . unless the four friends can get to Strand first. Aluna's plan is dangerous: pose as Upgraders and infiltrate the army. But the enemy isn't what they expected and the strategy begins to crumble. When the friends are torn apart by conflicting allegiances, their slim chance of avoiding war seems to disappear completely. For Aluna and Hoku, what began as a quest to save their own people has become a mission to save the world. But do Aluna and her friends have any hope of defeating Strand if they can't take him on together?