A mysterious alien named Avi arrives in Pine Tree Mountain and befriends Bramble. Bramble gradually learns that Avi's people, the Rhyot, originated from Earth. Millions of years ago, a highly developed Rhyotan civilization thrived to the detriment of Earth's environment. In the end, the Rhyotans had to flee their home planet. When Avi leads Bramble to the ancient relics of his people, a high-tech human army using all sorts of weapons attacks them both.

What's the purpose of Avi's trip back to Earth? Will he be able to protect his homeland this time?