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 Episode 1 - Warriors of the Deep (1)

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, intent on eradicating the upstart human race and reclaiming the planet… Air Date : 5th-Jan-1984

Season 21 Episode 1 - Warriors of the Deep (1)

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, intent on eradicating the upstart human race and reclaiming the planet… Air Date : 5th-Jan-1984  Read More

Season 21 Episode 2 - Warriors of the Deep (2)

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, but is the level-headed commander one who'll listen? Air Date : 6th-Jan-1984  Read More

Season 21 Episode 3 - Warriors of the Deep (3)

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. Air Date : 12th-Jan-1984  Read More

Season 21 Episode 4 - Warriors of the Deep (4)

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. Air Date : 13th-Jan-1984  Read More

Season 21 Episode 5 - The Awakening (1)

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 rather more realistic than planned... Air Date : 19th-Jan-1984  Read More

Season 21 Episode 6 - The Awakening (2)

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 if the Doctor can derail things, of course. Air Date : 20th-Jan-1984  Read More

Season 21 Episode 7 - Frontios (1)

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 threaten them originate from? Little does the Doctor suspect that somewhere nearby lurks a power capable of ripping even the TARDIS apart… Air Date : 26th-Jan-1984  Read More

Season 21 Episode 8 - Frontios (2)

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 discover the Tractators. Air Date : 27th-Jan-1984  Read More

Season 21 Episode 9 - Frontios (3)

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. Air Date : 2nd-Feb-1984  Read More

Season 21 Episode 10 - Frontios (4)

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, but how will they put it together again? Air Date : 3rd-Feb-1984  Read More

Season 21 Episode 11 - Resurrection of the Daleks (1)

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 the craft? And why are these two locations linked by the time corridor the TARDIS has been sucked into? Air Date : 8th-Feb-1984  Read More

Season 21 Episode 12 - Resurrection of the Daleks (2)

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. Air Date : 15th-Feb-1984  Read More

Season 21 Episode 13 - Planet of Fire (1)

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 worried? And why is Kamelion acting so erratically? Air Date : 23rd-Feb-1984  Read More

Season 21 Episode 14 - Planet of Fire (2)

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 guarantee the safety of his brother and the Sarn people, Turlough must consider a great personal sacrifice. Air Date : 24th-Feb-1984  Read More

Season 21 Episode 15 - Planet of Fire (3)

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 leader, the unbridled support he's sought in his campaign to cull the faithless from among his people. Turlough's secret past, however, is somehow intricately involved in all this, and the reluctance of its disclosure is enough to threaten all friendly ties with the Doctor. Air Date : 1st-Mar-1984  Read More

Season 21 Episode 16 - Planet of Fire (4)

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 guarantee the safety of his brother and the Sarn people, Turlough must consider a great personal sacrifice. Air Date : 2nd-Mar-1984  Read More

Season 21 Episode 17 - The Caves of Androzani (1)

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 spectrox, the substance they battle to control, so valuable? And how far will the Doctor go to protect his companion? Air Date : 8th-Mar-1984  Read More

Season 21 Episode 18 - The Caves of Androzani (2)

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? Air Date : 9th-Mar-1984  Read More

Season 21 Episode 19 - The Caves of Androzani (3)

The situation on Androzani Minor is building toward a violent confrontation, and the Doctor and Peri are slowly succumbing to spectrox toxemia. Air Date : 15th-Mar-1984  Read More

Season 21 Episode 20 - The Caves of Androzani (4)

Events on Androzani reach a bloody climax. Will the Doctor and Peri survive the carnage? And at what cost? Air Date : 16th-Mar-1984  Read More

Season 21 Episode 21 - The Twin Dilemma (1)

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 serve the giant slug Mestor? And what is Mestor's plan? Air Date : 22nd-Mar-1984  Read More

Season 21 Episode 22 - The Twin Dilemma (2)

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 spaceship crash in sight of a mound-shaped complex where no formalised structure should exist. Air Date : 23rd-Mar-1984  Read More

Season 21 Episode 23 - The Twin Dilemma (3)

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 after all. With or without help from the Doctor and his unpredictable mood swings, Lt. Lang is up for rescuing the twins, who are finally informed of the grand purpose they've been brought to Jaconda to accomplish. Air Date : 29th-Mar-1984  Read More

Season 21 Episode 24 - The Twin Dilemma (4)

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 they hope to thwart him despite his formidable ability at slipping into people's minds and controlling them. Air Date : 30th-Mar-1984  Read More