The story begins in the Andes mountains, where high school senior Burl Denning and his father notice a mysterious drop in the Sun's heat and light. Soon, the United States government contacts them, revealing that a strange station is siphoning solar energy and threatening to turn the Sun into a nova. Burl joins the crew of the Magellan, humanity's first experimental antigravity spaceship, commanded by Colonel Lockhart. Their mission is to journey across the solar system, disabling alien Sun-tap stations on Mercury, Venus, Mars, Jupiter's moons, Saturn, Uranus, and finally Pluto.
On Mercury, Burl discovers he possesses a unique energy charge that allows him to control the alien machinery. They navigate harsh environments, including the boiling surface of Mercury, the swampy oceans of Venus, and the insectlike civilization of Mars. Along the way, they battle rogue crew members manipulated by alien signals and encounter strange, frozen vegetation on the outer planets. Reaching the remote stronghold on Pluto, they uncover the chilling truth behind the solar siphon: a dying civilization attempting to warm a captured moon. The narrative culminates in a daring infiltration of the Plutonian citadel, leading to the liberation of strange alien captives from a galactic museum and the ultimate salvation of Earth.
