Troubled Storm won't risk losing someone else he loves. He won't let anyone in, especially Sky, who has a nasty habit of breaking through his defenses. Then he's taken off-world, and everything changes. Millions of artifacts spread throughout the globe need healing before the planet is safe, and only four teens can fix them. They must do the impossible, or Terra and another planet whose fate is entwined with ours will die. A looming war threatens to end humanity. A vicious alien has marked Jewel as his own against her will and would destroy the planet to claim her. Pax would give his life to free her. If either is lost, so is Terra. If every sentient species inhabiting our planet can cooperate, Terra may still be doomed. In this compelling conclusion of the Tetrasphere series, only one thing can save the planet now. Will they discover it in time?Readers who love Pittacus Lore's The Lorien Series and Rick Yancey's The 5th Wave series will love P.T.L. Perrin's action/adventure scifi Tetrasphere series. Get Terra's Anthem today, and if you haven't read the other books in the series yet, pick up Terra's Call, where it all begins. TEEN-YA SCIFI-ADVENTURE