第 12 季 共 20 集
播出时间：1974年12月29日
第 1 集 Robot (1)
播出时间：1974年12月29日
Can the Doctor, now in his fourth incarnation. Recover from his post regenerative trauma to save the Earth from Think Tank and their plot for world domination.
第 2 集 Robot (2)
播出时间：1975年1月5日
The Doctor and Sarah Jane become convinced Think Tank are behind the electronic component thefts but are unable to stop them carrying out another raid.
第 3 集 Robot (3)
播出时间：1975年1月12日
Sarah Jane and Kettlewell infiltrate an SRS meeting to try and find out what Miss Winters is up to but there is a surprise in store.
第 4 集 Robot (4)
播出时间：1975年1月19日
UNIT attempt to get into the bunker to stop Miss Winters setting off the world's nuclear missiles but first they have to get past the K1.
第 5 集 The Ark in Space (1)
播出时间：1975年1月26日
The Doctor's attempt to give Harry a trip in the TARDIS sees the two of them and Sarah Jane arriving onboard a space station in the far future, with some rather deadly security mechanisms.
第 6 集 The Ark in Space (2)
播出时间：1975年2月2日
The Doctor and Harry revive the Ark's medtech, Vira, to help Sarah Jane. But when station commander Noah is revived, he becomes suspicious of the newcomers.
第 7 集 The Ark in Space (3)
播出时间：1975年2月9日
Knowing that Noah has been infected by the Wirrn, the Doctor persuades Vira to halt the reviving of her people, knowing it will place them in danger as well.
第 8 集 The Ark in Space (4)
播出时间：1975年2月16日
The Doctor tries to protect the humans still in cryogenic suspension from the Wirrn, who are determined to use Earth as their new breeding ground.
第 9 集 The Sontaran Experiment (1)
播出时间：1975年2月23日
The Doctor, Sarah Jane and Harry teleport to Earth to ensure the planet is safe for the survivors on-board Nerva Beacon to return to Earth and re-inhabit their world. Only to find a Sontaran named Styre has captured a group of humans and conducting experiments on them to discover the human body's weaknesses, as part of the Sontaran's goal for domination of the galaxy.
第 10 集 The Sontaran Experiment (2)
播出时间：1975年3月2日
The Doctor learns that Styre has been experimenting on the Galsec crewmembers to pave the way for a Sontaran invasion of Earth and decides the only way to halt his plans is to challenge him to a duel.
第 11 集 Genesis of the Daleks (1)
播出时间：1975年3月9日
The planet Skaro, the distant past. The Time Lords divert the Doctor, Sarah Jane and Harry to this war-torn world, and give the Doctor a mission: the evil of the Daleks is about to be born here, and the Doctor is to try to ensure they evolve into less lethally aggressive beings - or, failing that, to avert their creation altogether. But has even the Doctor the right to commit genocide?
第 12 集 Genesis of the Daleks (2)
播出时间：1975年3月16日
The Doctor and Harry are taken to the Kaled bunker where Davros is preparing to demonstrate the Daleks, while Sarah Jane is captured by the Thals and taken to their city as a slave worker.
第 13 集 Genesis of the Daleks (3)
播出时间：1975年3月23日
The Doctor and Harry head to the Kaled city to alert the authorities to Davros' plans while Sarah Jane and Sevrin are forced to work on the completion of the Thals' rocket.
第 14 集 Genesis of the Daleks (4)
播出时间：1975年3月30日
The Doctor fails to prevent the Thals from destroying the Kaled city but they don't have long to enjoy their victory before the Daleks attack.
第 15 集 Genesis of the Daleks (5)
播出时间：1975年4月6日
The Doctor is forced to give Davros full details of future Dalek victories but opposition to Davros' plans is growing among the Kaleds and soon there is open rebellion.
第 16 集 Genesis of the Daleks (6)
播出时间：1975年4月13日
Gharman tries to convince the Kaleds to vote against the Dalek project but Davros has a trick up his sleeve, while the Doctor works to destroy the tape recording of Dalek victory and the Thals plan an intervention of their own.
第 17 集 Revenge of the Cybermen (1)
播出时间：1975年4月20日
The orbit of Jupiter, the 25th century. Arriving back on the Nerva Beacon much earlier in history, the Doctor and his friends discover the satellite beset by space plague while its crew struggles to keep space traffic away from Voga, the newest moon of Jupiter. But what is the connection between Voga, the plague, and some old enemies of the Doctor?
第 18 集 Revenge of the Cybermen (2)
播出时间：1975年4月27日
The Doctor transmits Sarah Jane and Harry down to Voga to cure Sarah Jane of the Cybermat's poison but Kellman's sabotage means he is unable to bring them back.
第 19 集 Revenge of the Cybermen (3)
播出时间：1975年5月4日
The Cybermen force the Doctor, Stevenson and Lester to carry bombs to the centre of Voga while Sarah Jane, Harry and Tyrum decide to contact Vorus.
第 20 集 Revenge of the Cybermen (4)
播出时间：1975年5月11日
The Doctor, Harry and Lester try to destroy the Cybermen's relay device, while the Vogans prepare to destroy Nerva even though Sarah Jane is still on board.
