'Shape Shifter' by Phil Ford

When two Mysteron agents break into the Laroux Foundation in Louisiana and attempt to sabotage its particle collider, they come face to face with Captain Scarlet; during the ensuing firefight a bullet shatters a container tank, releasing a strange, yellow gas into the atmosphere. The replicants escape into the sewers below, but Scarlet gives chase and kills them both; however, the Mysterons take over the gas and use it to create another Captain Scarlet, who promptly shoots the real Captain Scarlet dead, dumps his body in a nearby swamp, and then heads for Skybase. Captain Scarlet’s body is saved from being eaten by an alligator by a hick named Zachary and his father; the two men loot Scarlet of his equipment, and then decide to bury his body in the morning. Meanwhile, the fake Captain Scarlet arrives on Skybase, passes the routine DNA screening, and transforms himself into the appearance of anyone he touches. The following morning, the ersatz Scarlet attempts to assassinate Colonel White while he works out in the gym; Captain Blue tries to stop him, but the fake Scarlet’s shot goes wide and shatters a window. The Mysteron is instantly sucked outside as the air rushes out, but he manages to cling to the outer surface of Skybase. Zachary and his father bury Scarlet in a shallow grave, but are frightened off when the agent comes to life before their eyes; Scarlet makes his way to a Rhino concealed in a remote water tower, but the vehicle’s activation triggers an alarm that is immediately detected by Lieutenant Green. Scarlet contacts Spectrum and tries to warn his colleagues about the doppelganger, but White refuses to believe him; the Colonel is convinced that Scarlet has succumbed to Mysteron control, and he orders the Angels to destroy him. With some fancy driving, Scarlet manages to evade the Angels’ missile attack; he then returns to the Laroux Foundation, where he learns that the gas was an experimental form of pure atomic matter, able to assume any shape it is programmed with. Blue tracks Scarlet down and tells his friend that he believes his claims that he has been replicated; the two agents set off for Skybase – only to learn that the Mysteron replicant has now taken over the form of Colonel White and set the base’s controls on a collision course with the city of Houston…

Wayne Forester (Captain Scarlet), Robbie Stevens (Captain Blue / Captain Grey), Mike Hayley (Colonel White), Julia Brahms (Captain Ochre), Jeremy Hitchen (Captain Magenta), Jules de Jongh (Lieutenant Green / Harmony Angel), Emma Tate (Destiny Angel), Heather Tobias (Melody Angel)

Directed by David Lane
Executive Producer Gerry Anderson

TX:
UK (CITV):
12th November 2005 - shown in two parts within 'Ministry of Mayhem'

Notes:
*Featuring Captain Scarlet, Captain Blue, Captain Ochre, Captain Magenta, Captain Grey, Colonel White, Lieutenant Green, Destiny Angel, Harmony Angel and Melody Angel