In Colorado, mercenaries hired by Doc Terror stage a diversion to keep the Centurions busy by attempting to steal a shipment of plutonium. As they battle each other, Terror implements his plan to sink the entire city of Denver into a huge underground cavern and turn all of the city's inhabitants into cyborgs. The Centurions journey underground to get to the captive city and encounter Terror's new cyborg-enhanced mercenaries, who have stolen their exoframes. Weaponless, the Centurions have to figure out a way of saving both themselves and the city of Denver from Doc Terror's forces.

Science Lesson: Caves by Jake.

The Centurions visit Mexico at the behest of Max's old friend Rebecca. The location of the legendary Firebird, an ancient spaceship, was discovered at a Mayan temple, and she wants extra protection from a series of mysterious accidents that have been plaguing her expeditions. Kotan, one of her assistants, is working for Doc Terror, and requests extra help from Hacker. The Centurions manage to discover the location of the Firebird, but Hacker steals the ship and uses it against the Centurions. Together, they must pool their resources and clip Firebird's wings.

Science Lesson: The Mayans by Crystal.

Doc Terror switches a cyborg for the head of security, Captain Newman, at a secret installation, in order to steal the X-150, a smart missile that never loses track of a target. While transporting the missile, the Centurions come under attack, and Ace is knocked unconscious by a fall. Hacker plants a remote control circuit within his exoframe, so that Ace's movements in battle can be controlled by Doc Terror. Terror attacks again, and manages to steal the missile while Ace's weapons keep firing at Jake. The Centurions later try to get the missile back, but Ace's weapon systems keep firing at his team-mates. The remote control circuit is found, and together the Centurions attempt to destroy the missile as Doc Terror launches it towards Skyvault.

Science Lesson: Volcanoes by Max.