A rogue time-lord calling himself The Master (Roger Delgado), arrives on Earth and steals the Nestene energy unit from the National Space Museum. He hijacks the Beacon Hill Radio Telescope, which he uses to channel energy into the Nestene unit, and kidnaps Professor Phillips (Christopher Burgess) of the Ministry of Technology. The Doctor, his new assistant Jo Grant (Katy Manning), and Brigadier Lethbridge-Stewart of UNIT (Nicholas Courtney) investigate. At Beacon Hill, a time-lord appears and warns the Doctor about the Master, which allows him to bypass a trap. It appears the Time-Lords are keeping an eye on him in his Terran exile.
The Master seizes control of Farrel Autoplastics and builds Autons like those who invaded Earth in this Doctor’s first story, Spearhead from Space. Jo, there to investigate, is hypnotised by the Master. He sends her to UNIT with a booby-trap, but the Doctor is not fooled. UNIT traces the missing professor to Rossini’s Circus. The Doctor is captured there by Rossini (John Baskcomb), but Jo frees him. He steals something from The Master’s TARDIS, is attacked by Rossini’s men but rescued by policemen, though the Doctor realizes one of them is really an Auton.
The Doctor and Jo hide from the Autons in a quarry, where they are rescued by the Brigadier and his new UNIT Captain Mike Yates (Richard Franklin). Autons are all over the countryside, in carnival dress, handing out plastic daffodils. People are dropping from asphyxiation and heart attacks. The Master infiltrates UNIT in disguise. The Doctor and the Brigadier find one of the plastic daffodils at the plastics factory. As they are decoding it, a walkie-talkie activates it, nearly asphyxiating Jo. The Master tries to use a telephone he installed in UNIT HQ to strangle the Doctor, but the Brigadier saves him. The Master then breaks into HQ, but the Doctor has stolen the dematerialization circuit from the Master’s TARDIS and threatens to destroy it, which would leave the Master stranded on Earth, but he kidnaps Jo and takes both her and the Doctor to the quarry near the radio telescope, to force UNIT to call off an RAF strike on the Autons, but our heroes escape his clutches.
UNIT attacks the Autons, and the Doctor and the Brigadier pursue the Master into the radio-telescope’s control cabin. There, the Doctor convinces the Master that the Nestenes are incapable of telling the difference between humans and time-lords, and they will end up killing the Master as well. Working together, they force the Nestene energy back into space, and the Autons collapse. The Master flees, is caught, and Yates shoots him dead, but the Doctor pulls the mask off the body to prove it is not the Master after all, who has escaped. But the Doctor still has his dematerialization circuit and he can’t leave the Earth.
The Master was to be the Moriarty for the Doctor’s Holmes, with the Brigadier as his Watson. Robert Delgado was the perfect Master and re-appeared in seven more Third Doctor stories until the actor’s death in 1973, in an accident on a film-set at the age of 55, survived by his second wife Kismet. His evil charm and cool delivery made him the most popular humanoid enemy of the Doctor. Roger Caesar Marius Bernard de Delgado Torres Castillo Roberto had a Belgian mother and a Spanish father and was born in Cockney London. He appeared on the British stage (which you can tell the moment you hear him speak), TV, film, and radio. He was in Quatermass II. Jon Pertwee said he decided to leave Doctor Who in 1974 largely because of the loss of Delgado. In fact, fellow actors describe how Pertwee, when he got the news, went into the bathroom and howled.