When the Mysterons (voiced by Donald Gray) bizarrely threaten to "kill time", Colonel White (voiced by Donald Gray) sends the Spectrum captains to major cities to watch for potential targets. No promising intelligence surfaces until Captain Magenta (voiced by Gary Files) 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 neurosurgery. 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 (voiced by Charles Tingwell) assisting Magnus and his subordinates.