In the biggest, fastest spaceship ever designed by Swift Enterprises, Tom Jr. plans to make a grand tour of the planets in the solar system. But a group of criminal scientist's bent on conquering the universe is out to steal Tom's magnificent Cosmotron Express and destroy the young scientist and Swift Enterprises.

Determined to foil the fiendish plot, Tom and his pal Bud Barclay locate the enemy's fortress laboratory but are captured. The boys make a daring escape, only to be faced with an even more grim challenge in their next encounter with the enemy. Pursued on their phenomenal interplanetary journey, they become the targets of VIPER's frightening weapon, the enormous Orb.

How Tom, using his revolutionary device the Spider Crab, thwarts the feared, vicious leader of VIPER and his evil followers climaxes this gripping story of scientific combat.