Nicholas, the hypocritical ruler of the Zinba Empire, seeks to expand his domain by turning Earth into a private colony. His plan begins with annihilating Earth's defenses by destroying the city of Orion. While a group of young people vacation on Mars, they only realize the threat when they learn of the devastation on Earth. In an underground cave they meet Dr. Han and Fred, who believe that an immortal bird known as the Phoenix King resides somewhere on Earth. According to legend, this guardian of the planet is the only being capable of defeating Nicholas. The adventurers therefore set off toward the Phoenix’s supposed sanctuary, becoming Earth's sole hope.