Doctor Who: The Mutants

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The Mutants is the fourth serial of Doctor Who Season 9, originally broadcast in six episodes from 8 April to 13 May 1972. It was written by Bob Baker and Dave Martin and directed by Christopher Barry. It stars Jon Pertwee as the Third Doctor, Katy Manning as Jo Grant, and Paul Whitsun-Jones as the Marshal.

The Doctor and Jo are sent by the Time Lords to Skybase above the planet Solos with a sealed message for a native, and they find a harsh Earth Empire regime trying to force the world to change. As the Solonians suffer strange “mutations,” the Doctor learns these transformations are part of a natural life cycle tied to the planet’s seasons, while the Marshal pushes a dangerous scheme to remake the atmosphere.

Episode 1

The Time Lords intercept the TARDIS and send it to Skybase 4, an Earth Empire station orbiting the colony world Solos. A sealed capsule materialises inside the ship, stamped with Time Lord symbols and a single instruction: deliver it on Solos to the right recipient: whoever that is. The Doctor and Jo step into a tense ceremony where an idealistic Administrator is about to announce independence for Solos.

The Marshal, a hard-eyed military governor, seethes. During the speech a masked gunman strikes; the Administrator falls, and a young Solonian named Ky is framed for the murder. Chaos erupts. The Marshal tightens security, arrests the Doctor, and demands help with “order” on the planet below. Jo grabs the dropped Time Lord capsule as guards fire; she and Ky tumble into a transmat and vanish to the surface.

On Solos, night fog coils through ruined stations and black rock valleys. Jo catches breath, realises the capsule will not open for her or Ky, and hides as something tall and chitinous scuttles past. Back on Skybase the Marshal unveils his ace: Professor Jaeger, whose atmospheric experiments promise to make Solos “fit” for humans: whatever that does to the natives. The Doctor reads the figures and goes cold. This is not colonisation. It’s erasure by science.

Episode 2

On the planet, Jo and Ky pick their way through caverns etched with ancient symbols while patrols comb the surface. They are cornered by a looming, insectoid “Mutant,” which snarls and then, unexpectedly, backs away from Jo’s calm voice. Ky insists these creatures were once his people. On Skybase, the Marshal interrogates the Doctor and waves Jaeger’s plan like scripture: bombard Solos’s air with rockets to “stabilise” it.

The Doctor calls it reckless and is marched to help anyway. He uses the distraction to escape in a transmat capsule, landing amid dust storms and shattered domes. Jo, flagging, collapses; Ky leads the Doctor through a maze of tunnels toward a hideout whispered about among rebels. They encounter Varan, a proud Solonian collaborator, now betrayed by the Marshal and already feverish with a strange skin bloom.

Above, Jaeger conducts a small-scale trial; weather howls, and crops wither in minutes. The Doctor studies cave crystals that glow at certain radiations and realises Solos is not “wrong”. It is cyclical, its life adapted to transform with the planet. The Time Lord capsule still refuses to open. He turns it in the cavern light and sees etched runes match wall markings. Perhaps the planet itself is the key.

Episode 3

The Doctor follows the glyphs deeper and meets Sondergaard, a missing Earth scientist everyone assumed dead. He has lived among the caves for years, decoding murals and learning that the “mutations” are a natural metamorphosis in the Solonian life cycle. He treats Jo’s sickness with a crystal that hums against the ambient radiation, then guides the Doctor to the “old city,” where inscriptions speak of seasons measured in centuries.

In that light the Time Lord capsule clicks and opens: for Ky. Inside lie etched tablets and a small facet of crystal, instructions for a rite of change. On Skybase, Jaeger scales up his tests and the Marshal cements a coup, using Varan’s growing deformities to stoke human fear. Varan, raging, returns to the station to confront his masters and finds only mockery; his transformation accelerates and he flees into ducts.

Patrols sweep the planet, driving Solonians out of shelters; Jo dodges gunfire and helps carry supplies to a crystal-lined chamber that hums like a heart. The Doctor reads the tablets: catalyse, don’t cure; guide, don’t poison. He resolves to show both sides the truth. Above, the Marshal orders full deployment of Jaeger’s rockets. The Doctor looks from Ky to the sky and starts building a lamp.

Episode 4

Skybase turns into a command post for planetary surgery. Jaeger’s teams load warheads; technicians talk about “parameters” while the Doctor, dragged back to the station, is told to correct their maths. He bargains for time and introduces tiny “errors” that will blunt the bombardment. On the surface, Sondergaard and Jo prepare a chamber with the crystal facet and a lattice of cave stones; Ky steps inside, afraid and determined.

Varan, half-metamorphosed and out of options, hijacks a shuttle and crashes it into Skybase’s docking rim, tearing open the Marshal’s rhetoric with alarm klaxons. The Marshal labels it “Mutant terrorism” and clamps down harder, broadcasting orders that dehumanise Solonians as targets. The Doctor is forced to stabilise Jaeger’s array or watch prisoners die. He chooses a third path: make the rockets safe enough to fail.

In the caverns, the first wave of artificial weather hits; winds shriek; the crystal field shatters and Ky is flung back, change incomplete. Sondergaard insists the process needs a purer catalyst from the deepest vein. Jo volunteers to go with him. Above, Jaeger grins as launch confirms. The Doctor’s hands fly over controls, pinning hope on miscalibration. If he’s wrong, the planet will be sealed in someone else’s image forever.

Episode 5

Jaeger’s bombardment slams into Solos and does not settle the air; it scorches it. Fields bleach to ash, animals die, and shock fronts ripple across the caves. The Marshal blames “native sabotage” and prepares a toxin purge to finish the job. The Doctor openly defies him and is hurled into a cell. Jo and Sondergaard squeeze through a fissure to a chamber of pure crystal: raw, singing, almost alive.

They prise free a shard that dazzles their eyes, then dodge patrols to reach Ky, who trembles between forms. On Skybase, the Doctor cons a guard, slips back into Control, and recodes Jaeger’s guidance so any second strike will crater uninhabited highlands, not settlements. Varan, dying but lucid, floods a corridor to slow the Marshal’s soldiers and buys minutes with his life. In the crystal chamber, Sondergaard builds a focused lamp while Jo steadies Ky’s hands.

They bathe him in tuned light. His outline blurs. Fingers lengthen, pupils flare gold. He looks at Jo and smiles with new calm. Above, the Marshal orders executions and drags the Doctor to the viewport to watch a planet “made clean.” Warning lights flicker as Jaeger’s own figures betray him. The Doctor breathes out; he still needs a miracle.

Episode 6

The miracle walks in. Ky emerges fully transformed: tall, luminous, his voice like the cave’s song. He rises through a shaft and glides into Skybase with Sondergaard and Jo behind him. Guards fire and lower their guns, awed. Ky demands an end to interference and a reckoning for the dead. Jaeger blusters, lunges for controls, and dies beneath a collapsing gantry as the Doctor’s “safe failure” finally bites.

The Marshal, cornered by truth and cameras, orders a massacre; Ky lifts a hand and energy ripples freeze weapons mid-fire. He names the Marshal guilty of genocide. The man reaches for a last pistol and is engulfed in a flare that leaves only a shadow. Silence follows. Sondergaard addresses Earth Central down a wideband link: Solos is not a mine but a living world with citizens who change as the planet changes.

Withdrawal orders crackle back; the Empire is already fading elsewhere. The Doctor asks Ky what comes next. “Teach our young,” he says, “and wait for the next season.” Jo squeezes the Doctor’s arm, smiling at Sondergaard’s decision to stay as friend and translator. The TARDIS hums. As they depart, Solos darkens into a cool, starry night, its own night, while, far below, crystal halls sing of a future chosen, not imposed.

Themes

Measured against its neighbours, The Mutants trades naval spectacle and castle intrigue for a pointed, political parable. It isn’t as breathless as The Sea Devils or as baroque as The Dæmons, and its pacing sits a notch below the tautness of Day of the Daleks.

Yet its decolonisation theme, world-building on Skybase, and stark moral choices place it alongside Colony in Space and The Ambassadors of Death for adult bite. Ambitious, uneven, but resonant, it lands as upper-mid-tier Pertwee: a story whose ideas linger longer than its fireworks.

Link-wise, it extends the Time Lords’ “mission brief” thread from Colony in Space and The Curse of Peladon, pointing toward the loosening of exile that culminates in The Three Doctors. Its portrait of an overreaching Earth Empire foreshadows the geopolitical sweep of Frontier in Space and contrasts with the Federation diplomacy revisited in The Monster of Peladon.

The show’s critique of exploitation and environmental tampering anticipates the reckoning of The Green Death, while its cautionary science echoes into later moral puzzles throughout the era. Sitting between The Sea Devils and The Time Monster, The Mutants widens the canvas and sharpens the UNIT years’ conscience.

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This is a chapter from Craig Hill’s book “Doctor Who – The Third Doctor”, chronicling every episode featuring the Third Doctor. It is available on Amazon.

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