The Secret of the Ninth Planet features easily identifiable characters; a suspenseful, dangerous situation; and a plot that is almost nonstop action. Such an action-oriented novel requires a strong premise. The characters need a good reason for their desperate acts of courage against great odds. The threat in this novel is to planet Earth itself.

Alien beings are stealing the sun's energy, making Earth and Mars dangerously frigid and threatening crop failures on Earth. Furthermore, astronomers discover that the sun-tapping installations will cause the sun to become a nova; in a matter of weeks the sun will suddenly expand into a red giant and destroy the inner planets of the solar system.

Ordinary chemical-propelled spaceships would take weeks just to reach the nearest planets, but the Magellan can travel much faster than ordinary spacecraft. By making the Magellan the only craft capable of traveling fast enough...