Doctor Who: Season 21
The Twin Dilemma, the first story with Colin Baker as the Sixth Doctor, aired last in the season. This season saw the departure of companions Tegan, Turlough and Kamelion and introduced Peri. Most episodes were the traditional twenty-five minute length. However, due to coverage of the 1984 Winter Olympics, Resurrection of the Daleks was re-edited before airing and shown as two forty-five minute episodes.
Season 21 Lore Primer
Key plot threads, lore context, and character stakes you need to remember before diving into this season.
- Directly follows the overarching narrative developments of Doctor Who Season 20.
- Faction dynamics and core character alliances shift under escalating external stakes.
- Crucial mysteries introduced previously reach key turning points and narrative reckonings.
- Sets up serialized story arcs that build directly toward the climactic season finale.
Season overview
The Twin Dilemma, the first story with Colin Baker as the Sixth Doctor, aired last in the season. This season saw the departure of companions Tegan, Turlough and Kamelion and introduced Peri. Most episodes were the traditional twenty-five minute length. However, due to coverage of the 1984 Winter Olympics, Resurrection of the Daleks was re-edited before airing and shown as two forty-five minute episodes.
Episode Guide
Season 21 Progress Shield
Warriors of the Deep (1)
Jan 5, 1984 · 25 min
Earth's ocean floor, 2084. With two superpowers poised on the brink of a devastating photonic war, a missile base comes under attack from the reptilian Sea Devils and Silurians, in
Warriors of the Deep (2)
Jan 6, 1984 · 25 min
Just as the Doctor gains a tentative trust from the humans, a Silurian battle cruiser approaches. The Doctor warns Commander Vorsha to hold his fire and find out what they want, bu
Warriors of the Deep (3)
Jan 12, 1984 · 25 min
As Vorshak's crew are cut down by Sauvix's Sea Devil Warriors, the Doctor is running out of ways to broker a peace between the opposing species.
Warriors of the Deep (4)
Jan 13, 1984 · 25 min
With Silurians in control of the base, Icthar reveals his plan for a final solution to Earth's human problem, which presents the Doctor a great moral dilemma.
The Awakening (1)
Jan 19, 1984 · 26 min
The sleepy English village of Little Hodcombe, 1984. The village re-enactment of the English Civil War is in full swing, but a malign alien presence intends the mock-battles to be
The Awakening (2)
Jan 20, 1984 · 25 min
The Malus, an alien that's purely evil, needs the civil war re-enactments to become authentic so it can feed off the psychic energy of dying and embattled men and fully revive. Not
Frontios (1)
Jan 26, 1984 · 25 min
The planet Frontios, in the distant future. Following Earth's destruction, a tiny colony struggles to eke out a life on this desolate world. But where do the bombardments that thre
Frontios (2)
Jan 27, 1984 · 25 min
Following the destruction of the TARDIS, the only part of it left is the hat stand. So Turlough uses it as a weapon! Plantagenet gets swallowed by the earth, and Norna and Turlough
Frontios (3)
Feb 2, 1984 · 25 min
Trying to rescue the Doctor from the Tractator's trap, Tegan lands them both in even more trouble. Turlough goes a bit mad, and reckons he knows the evil of the Tractators from old
Frontios (4)
Feb 3, 1984 · 25 min
The Doctor tries to deal with the Tractator's cunning plan, despite Turlough's best intervention. They discover the splintered TARDIS in the tunnels beneath the planet's surface, b
Resurrection of the Daleks (1)
Feb 8, 1984 · 46 min
London's Docklands, 1984. Why are uniformed policemen gunning down strangely-dressed vagrants in broad daylight? A prison ship in the far future - who is the sole prisoner aboard t
Resurrection of the Daleks (2)
Feb 15, 1984 · 46 min
As the surviving station crew work to destroy the space station, Davros consolidates his power and the Daleks launch a fiendish scheme to use the Doctor against the Time Lords.
Planet of Fire (1)
Feb 23, 1984 · 25 min
Lanzarote, 1985. Archaeologist Howard Foster raises a strange metal artefact from the sea floor. But how is it linked to the signal the TARDIS received? Why is Turlough suddenly so
Planet of Fire (2)
Feb 24, 1984 · 25 min
While the Master, victim of his own attempt to improve his TCE weapon, seeks restoration through Sarn's numismaton gas, the truth of Turlough's past comes out at last, though to gu
Planet of Fire (3)
Mar 1, 1984 · 24 min
Sarn prophesy foretells of an outsider who will come to aid the people. It's a role the Master is more than delighted to fill, which finally presents Timanov, the Sarn religious le
Planet of Fire (4)
Mar 2, 1984 · 25 min
While the Master, victim of his own attempt to improve his TCE weapon, seeks restoration through Sarn's numismaton gas, the truth of Turlough's past comes out at last, though to gu
The Caves of Androzani (1)
Mar 8, 1984 · 25 min
The planet Androzani Minor, the distant future. In the planet's caves war rages between government troops and the android warriors of the mysterious Sharaz Jek. But what makes spec
The Caves of Androzani (2)
Mar 9, 1984 · 26 min
The Doctor and Peri have been rescued from the firing squad by the mysterious Sharaz Jek. But he has his own plans for them. And why are they suddenly feeling ill?
The Caves of Androzani (3)
Mar 15, 1984 · 25 min
The situation on Androzani Minor is building toward a violent confrontation, and the Doctor and Peri are slowly succumbing to spectrox toxemia.
The Caves of Androzani (4)
Mar 16, 1984 · 26 min
Events on Androzani reach a bloody climax. Will the Doctor and Peri survive the carnage? And at what cost?
The Twin Dilemma (1)
Mar 22, 1984 · 25 min
Earth, the future. The genius Sylvest twins, child prodigies, are kidnapped by the mysterious Professor Edgeworth and taken to the planet Jaconda. But who is Edgeworth? Why does he
The Twin Dilemma (2)
Mar 23, 1984 · 26 min
The Doctor takes Peri to Titan 3, a desolate hunk of rock in space where he hopes to find some solitude for a while. Instead he finds the lone but unconscious survivor of a recent
The Twin Dilemma (3)
Mar 29, 1984 · 25 min
The Doctor arrives on Jaconda, once lush and green, to find it completely devastated by giant gastropods. Old legends about the planet's half-human/half-slugs weren't just myths af
The Twin Dilemma (4)
Mar 30, 1984 · 26 min
The Doctor and Edgeworth deduce that the real plan of Mestor, the gastropod ruler of Jaconda, will not only destroy Jaconda but lead to the devastation of other planets. Together t