When a mysterious and top-secret alien probe, which Tom found on Jupiter, is stolen from Swift Enterprises, Tom Swift rockets into another exciting mission. The information locked in the probe is invaluable, and Tom must find it at all costs. He and his friends, Anita and Ben, chase the thief through underground caverns and, using their high-powered space-ships, through the blackness of space--risking everything they have to find the alien probe and reveal its secrets.