A G-Reaction engine powered bullet train disappears in a flash of light, setting Billy and Penny off on a race to uncover the secrets behind an alien invasion.

Helmet worms capture Lotta and Penny, taking them to the enemy's secret base; James and Captain Clayton try to destroy the alien's advanced weaponry.

A surprise terrorist attack injures Captain Clayton and James; Penny learns the identity of the bomber; aliens transform deceased hostages into weapons.

Lotta solves a problem that even the most brilliant minds cannot solve; Billy and Penny undertake a daring rescue mission.

Ace pilot James tries to destroy an alien base; Penny searches for clues; Billy discovers an extra-terrestrial mind control plot.

Billy and Penny work together to locate Element X and make a last-ditch attempt to destroy the alien navigation system.