This season saw the introduction of the Black and White Guardians as well as the companion Romana, who became only the second female Time Lord companion since Susan. This season is sometimes colloquially known as The Key to Time season after the story arc involving the Key to Time. Although not the first season to consist of linked stories (Season 8 in 1971 was the first, as all the stories that year featured the Master), it was the first to be recognised as having a series long arc. Although multi serial arcs would occur again, such a full- season experiment wouldn't be attempted again until Season 23. The arc has a number of similarities to the Season 1 story The Keys of Marinus. The storyline was originally proposed for Season 15, but it required more planning.
Episodes
E1
1. The Ribos Operation (1)
6.6
September 2, 1978
25 min
The Magellanic Clouds, the planet Ribos, an unknown time. Ordered by the White Guardian to collect the pieces of the omnipotent Key to Time, The Doctor, K-9 and his new assistant Romana arrive. Collecting the first segment is not going to be easy…
Cyril Luckham, Iain Cuthbertson, Nigel Plaskitt, Paul Seed, Robert Keegan
E2
2. The Ribos Operation (2)
6.7
September 9, 1978
25 min
Trying to obtain the first segment of the Key to Time, the Doctor and Romana are swept up in an elaborate con. The target – the homicidal Graff Vynda K.
Guest Stars:
Iain Cuthbertson, Nigel Plaskitt, Paul Seed, Robert Keegan, Prentis Hancock
E3
3. The Ribos Operation (3)
6.7
September 16, 1978
25 min
Prisoners of the maniacal Graff Vynda K, the Doctor and Romana must break out and pursue the first segment – even as Unstoff takes it into the most dangerous place on Ribos.
Guest Stars:
Iain Cuthbertson, Nigel Plaskitt, Paul Seed, Robert Keegan, Prentis Hancock
E4
4. The Ribos Operation (4)
6.7
September 23, 1978
25 min
Trapped in the catacombs between a mad warlord and ravenous monsters, the Doctor and Romana work desperately to obtain the segment of the Key to Time - and escape alive.
Guest Stars:
Iain Cuthbertson, Nigel Plaskitt, Paul Seed, Robert Keegan, Prentis Hancock
E5
5. The Pirate Planet (1)
7.4
September 30, 1978
25 min
Planet Zanak, unknown time. The Doctor and Romana are seeking the planet Calufrax where the second segment waits. They are in the right place and the right time… but on the wrong planet.
Guest Stars:
Bruce Purchase, Andrew Robertson, Ralph Michael, David Sibley, David Warwick
E6
6. The Pirate Planet (2)
7.7
October 7, 1978
25 min
The Doctor begins to investigate the mysteriously wealthy planet Zanak. Mentiads, a deranged Captain, strange omens, miraculous mines – what does it all mean? And what does it have to do with the Key to Time?
Guest Stars:
Bruce Purchase, Andrew Robertson, Ralph Michael, David Warwick, Primi Townsend
E7
7. The Pirate Planet (3)
7.7
October 14, 1978
25 min
The Mentiads take the Doctor, Romana and Kimus to a reunion with K9 and Mula, where they set about trying to defeat the Captain.
Guest Stars:
Bruce Purchase, Andrew Robertson, David Sibley, David Warwick, Primi Townsend
E8
8. The Pirate Planet (4)
7.6
October 21, 1978
25 min
The Captain and Xanxia work toward their secret goals. Both depends on the pirate planet consuming one more victim - Earth.
Guest Stars:
Bruce Purchase, Andrew Robertson, David Sibley, David Warwick, Primi Townsend
E9
9. The Stones of Blood (1)
7.8
October 28, 1978
25 min
England, the late 1970s. The Doctor and Romana arrive in search of the third segment. But the Tracer readings are erratic and something ominous is happening with an ancient stone circle...
Guest Stars:
Beatrix Lehmann, Susan Engel, Nicholas McArdle, Elaine Ives-Cameron
E10
10. The Stones of Blood (2)
7.6
November 4, 1978
25 min
The quest for the Third Segment has landed the Doctor and Romana in the midst of a druidic cult centred on a stone circle. But the stones are not what they seem, and somewhere out there is a blood-thirsty Celtic goddess.
Guest Stars:
Beatrix Lehmann, Susan Engel, Nicholas McArdle, Elaine Ives-Cameron
E11
11. The Stones of Blood (3)
7.6
November 11, 1978
25 min
Chased by blood-thirsty stones, the Doctor must find a way to rescue Romana. What awaits him in the theoretical absurdity of hyperspace?
Guest Stars:
Beatrix Lehmann, Susan Engel, Gerald Cross, David McAlister, James Murray
E12
12. The Stones of Blood (4)
7.6
November 18, 1978
25 min
Facing a sentence of death from merciless justice machines, the Doctor must play for time while Romana tries to discover just who Vivian Fey really is.
Guest Stars:
Beatrix Lehmann, Susan Engel, Gerald Cross, David McAlister
E13
13. The Androids of Tara (1)
7.0
November 25, 1978
25 min
Arriving on Tara, Romana locates the fourth segment of the Key to Time with ease. But getting it away proves more difficult, as she is captured by the scheming Count Grendel who wants the throne of Tara for himself.
Guest Stars:
Peter Jeffrey, Simon Lack, Neville Jason, Paul Lavers, Lois Baxter
E14
14. The Androids of Tara (2)
6.7
December 2, 1978
25 min
The Doctor must employ a desperate gambit to keep the evil Grendel off the throne. And the Count has a new pawn to play - Romana.
Guest Stars:
Peter Jeffrey, Simon Lack, Neville Jason, Paul Lavers, Lois Baxter
E15
15. The Androids of Tara (3)
6.8
December 9, 1978
25 min
The battle for control of Tara turns into a duel of wits between the Doctor and Grendel. But the Count shows he has more treacherous tricks up his sleeve.
Guest Stars:
Peter Jeffrey, Simon Lack, Neville Jason, Paul Lavers, Lois Baxter
E16
16. The Androids of Tara (4)
6.8
December 16, 1978
25 min
Grendel plans two weddings and a funeral to cement his hold over Tara. The Doctor and K-9 race to foil him and save the Time Lady's life.
Guest Stars:
Peter Jeffrey, Simon Lack, Neville Jason, Paul Lavers, Declan Mulholland
E17
17. The Power of Kroll (1)
5.5
December 23, 1978
25 min
The Third Moon of Delta Magna, The Future. The Doctor and Romana arrive in search of the fifth segment and are immediately swept up in a conflict between the crew of a new refinery and the embittered natives…
Guest Stars:
Neil McCarthy, John Abineri, Philip Madoc, Glyn Owen, Carl Rigg
E18
18. The Power of Kroll (2)
5.6
December 30, 1978
25 min
The Doctor and Romana try to avoid being sacrificed to Kroll – just in time for the real monster to appear.
Guest Stars:
Neil McCarthy, John Abineri, Philip Madoc, Glyn Owen, Carl Rigg
E19
19. The Power of Kroll (3)
5.6
January 6, 1979
25 min
The massive Kroll is awake and killing anyone in its path. And the swampies are determined to appease it – by sacrificing the Doctor and Romana.
Guest Stars:
Neil McCarthy, John Abineri, Philip Madoc, Glyn Owen, Carl Rigg
E20
20. The Power of Kroll (4)
5.6
January 13, 1979
25 min
The Doctor and Romana are trapped between the monstrous Kroll and the insane refinery commander. And there is no sign of the fifth segment of the Key to Time.
Guest Stars:
Neil McCarthy, John Abineri, Philip Madoc, Carl Rigg, Frank Jarvis
E21
21. The Armageddon Factor (1)
6.8
January 20, 1979
25 min
Searching for the sixth segment, the Doctor and Romana land in the midst of a brutal nuclear war between the planets Atrios and Zeos.
Guest Stars:
John Woodvine, Lalla Ward, Davyd Harries, Ian Liston, Susan Skipper
E22
22. The Armageddon Factor (2)
6.7
January 27, 1979
25 min
Swept up in an apocalyptic war, the Doctor must help the Marshal defend his planet. But who or what controls the Marshal?
Guest Stars:
Harry Fielder, John Woodvine, Lalla Ward, Davyd Harries, Ian Saynor
E23
23. The Armageddon Factor (3)
6.9
February 3, 1979
25 min
The Doctor meets a new enemy – the Shadow – who wants the Key to Time. And the Atrian-Zeon war is approaching an awful climax.
Guest Stars:
John Woodvine, Lalla Ward, Davyd Harries, William Squire, Iain Armstrong
E24
24. The Armageddon Factor (4)
6.6
February 10, 1979
25 min
The Doctor is forced into a desperate gambit to prevent a massacre. But it is getting harder to tell friend from foe.
Guest Stars:
John Woodvine, Lalla Ward, Davyd Harries, William Squire, Pat Gorman
E25
25. The Armageddon Factor (5)
6.4
February 17, 1979
25 min
The Doctor and Romana finally venture into the Shadow's lair. The Shadow appears to hold all the cards but the Doctor has found an old friend.
Guest Stars:
Lalla Ward, William Squire, Barry Jackson
E26
26. The Armageddon Factor (6)
6.7
February 24, 1979
25 min
The Doctor and the Shadow have their final confrontation to take control of the Key to Time. Completing it may entail an awful sacrifice. And the Black Guardian will do anything to obtain it and plunge the Universe into chaos.
Guest Stars:
John Woodvine, Lalla Ward, Davyd Harries, Valentine Dyall, William Squire