Grey Skulls is the twelfth episode of Series 2 of Gerry Anderson's New Captain Scarlet. However, in the series' original 2005 broadcasts on Ministry of Mayhem, the episode erroneously aired as the series finale.


After the Mysterons take over a Phoenix policeman named Rimmer and use him to steal a canister of deadly alien spores brought back by a space probe from Ganymede, Captain Scarlet and Captain Blue are ordered to give chase. Elsewhere, two rival bikers – Colt from the Grey Skulls and Brock of the Wolf Pack – are meeting to discuss a possible peace treaty when they are interrupted by the arrival of Rimmers police car; as the cop takes refuge inside a nearby building a Spectrum Rhino draws up, which trashes Colts motorcycle in the process. Brock is killed by Rimmer and recreated by the Mysterons; the biker then takes over possession of the canister as Rimmer disappears into thin air. Captain Ochre arrives to assist her comrades in the hunt for Rimmer; however, Colt immediately sees a way to replace his ruined bike, and promptly steals Ochres Stallion Raid Bike. Unable to find their quarry, the three Spectrum agents return to Skybase, where a furious Colonel White orders Ochre to recover her stolen bike before its firepower can be misused. Using Lieutenant Greens information that the Grey Skulls are based in Roswell, a chastened Ochre heads off to New Mexico to track down the Raid Bike. Having 'persuaded' two Grey Skull gang members to take her to their leader Ochre confronts Colt – only to have him blow up her Cheetah RRV with the Raid Bikes weaponry. Colt then takes Ochre to his base inside a disused underground military bunker, where he and his gang are waging a war against the alien invaders first sited in the area in the 1950s. Meanwhile, Scarlet and Blue determine that the Mysterons target is the new Stellar City theme park in Phoenix; however, the two agents are still looking for Rimmer – unaware that it is now Brock who is about to release the deadly spores that will kill literally thousands of visitors…