Major Mars was born on the Moon to Earth parents, and he has devoted his life to maintaining peace between the planets. He is a wizard of science and an inventor who created Grag, his robot assistant. Grag has a synthetic brain that enables speech and thought. In 3964, the Major is sent on a mission by the President of Earth to stop the Emperor of Jupiter from turning the residents of the Jupiter colony into beast men. With the assistance of Joan Jilson, daughter of the colony's governor, Major Mars is able to stop Emperor Kells and cure the people transformed into beasts. The Major has a lot of equipment such as a space ship with a sophisticated lab, a ray gun, a micro television wrist communicator, an anti-gravity belt, an invisibility ray, and a laser gun.