Judith "Judy" Chapman (voiced by Sylvia Anderson) is the central antagonist in the episode Place of Angels.
She was a research assistant from a research centre in Manchester who was killed and reconstructed as a agent by the Mysterons (strange alien beings from Mars who held a vendetta against the Earth and had the ability of retro-metabolism, so they could reconstruct anything or anyone and use them for their own ends) with the orders to carry out their threat of destroying the "Place of the Angels".
One evening Judy was at the research centre with her mentor Dr. Denton at the research centre, watching him perform a experiment with a deadly virus called K14. It looked harmless, but Denton assured her that there was another in just one test tube to wipe out a city of ten million people. Worse of all it is so deadly that the human body has no defence against it.
After an electronic check at the gates, Judy drives home, but the Mysterons' chief agent Captain Black deliberately places a tanker filled with explosive fuel in her route. Judy only spots it at the last second.
Despite braking hard, she crashes into the truck and the impact kills her. The Mysterons then use their powers of retro-metabolism to reconstruct her before the tanker explodes.
After a while an exact likeness of Judy Chapman is standing next to Captain Black with handbag and all.
Next morning after receiving her instructions from the Mysterons, Judy returns to the research centre and after another electronic check drives inside.
She sees the guard and uses the arms that are for holding test tubes in safety to choke the guard to death. Afterwards she goes inside the lab and steals the phial of K14 virus.
Meanwhile Spectrum sends agents Captain Scarlet and Captain Blue to investigate and counter the Mysterons' latest threat.
Judy is then seen on a plane with the K14 stored in her handbag. The Captain says that they will be landing at New York Airport in ten minutes.
She then commandeers a car and drives down the inner state highway. Captain Scarlet and Captain Blue pursue her in a Spectrum Pursuit Vehicle, but Captain Black is watching and warns her of their pursuit so Judy stops the car, gets out and lets it drive down the hill, crashing into a tree. She also craftily leaves behind what looked like a shattered phial containing the virus. While Spectrum run tests to see if the phial really did contain the deadly virus, Judy is well on her way still carrying the virus and flying through many more states including Miami, Goosebay, Canada and Los Angeles which is the Spanish word for "The Angels" and is the Mysterons' chosen target.
After landing in Los Angeles, she drives away from the city and to the main reservoir at the Boulder Dam, where she will pour the virus into the city's water supply, which is the quickest and deadliest way to spread it. Spectrum catches onto the whereabouts of Judy and Captain Scarlet and Captain Blue follow her in a Spectrum Passenger Jet.
Captain Scarlet then parachutes onto the dam from 500 feet, but Judy sees the plane and shoots him before he reaches the ground, weakening him. She then fumbles in her handbag and gets out the phial, which she intends to drop into the reservoir. Captain Scarlet aims his pistol at her, shouting for her to stop. The Mysteron agent says that he is too late.
Captain Scarlet warns her that if she makes one move he will shoot. Judy takes a step backward, and Captain Scarlet fires a shot, making good on his threat. As she is walking back, one of her high heels gets caught and breaks off on a drain, causing her to lose her balance and fall off the dam to her death. However Captain Scarlet manages to recover the phial and saves Los Angeles, thereby foiling the Mysterons' plan.