The Adventures Of Kali Audoo: The Skyborn Discovery by V.M. Robinson

When Kali leaves her quiet life in Illinois and boards the magic train to the mesosphere, she carries more than a bow and a secret past — she carries the weight of a prophecy tied to the sky itself. The Guardian knows that once she steps beyond Earth and into the realm above, her role shifts from protector to guide, and the truth she has guarded for years must finally be revealed. Above the mesosphere lies a hidden planet frozen in time, divided into two kingdoms and haunted by giant creatures chained in ancient caves — a world Kali was never meant to discover alone.