"When the Mysterons bizarrely threaten to "kill time", Colonel White sends the Spectrum captains to major cities to watch for potential targets. No promising intelligence surfaces until Captain Magenta discovers that the Commander of Western Region World Defence, General J.F. Tiempo – whose surname means "time" in Spanish – is at a clinic in England to undergo brain surgery. Believing that Tiempo's life is in danger, White has him flown to Cloudbase with his surgeon, Dr Magnus, who insists that the operation – to be carried out with the aid of a pioneering medical device called the "cerebral pulsator" – go ahead as planned. White reluctantly agrees and allows him to use their sickbay as an operating theatre, with Cloudbase's medical officer Dr Fawn assisting Magnus and his subordinates.
Unknown to Spectrum, Magnus is a Mysteron reconstruction of the original doctor, who has been killed in a road accident engineered by Captain Black. During the operation, the reconstruction deliberately overruns the pulsator, inducing a seizure that kills his masked patient. Fawn removes the mask to reveal the face of Captain Scarlet, who unknown to Magnus had substituted for Tiempo. Exposed as a Mysteron agent, Magnus breaks out of sickbay and flees to Cloudbase's generator room. He is cornered by Captain Blue and killed when he is knocked against a bare cable.
During this time, an abnormality has appeared on one of pre-operative radiographs taken of Tiempo's head: Magnus's hand, which was accidentally caught in the image, has blocked the X-rays and is registering as solid flesh. With Tiempo saved and Scarlet revived thanks to his retro-metabolic powers, White announces that Spectrum will develop technology to exploit the Mysterons' imperviousness to X-rays and vulnerability to electricity."
Check out the "Red Screen of Death" in Snap 62.