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Season guide

Doctor Who: Season 20

22 episodes Premiered Jan 3, 1983 Updated Sep 25, 2026

Structurally, the season retread season 18's formula of including a trilogy of stories bound together by an overarching theme. In this instance, the tripartite tale involved Turlough's attempts to kill the Doctor at the behest of the Black Guardian.

Previously on Doctor Who

Season 20 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 19.
  • ⚡ 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

Structurally, the season retread season 18's formula of including a trilogy of stories bound together by an overarching theme. In this instance, the tripartite tale involved Turlough's attempts to kill the Doctor at the behest of the Black Guardian.

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Season 20 Episodes

Episode Guide

🛡️ SPOILER SHIELD

Season 20 Progress Shield

Future titles & synopses blurred. Tap "Reveal" on any card to peek.
Binge Efficiency Engine

Season 20: Filler vs. Essential Canon

Filter episodes by narrative weight. Focus on essential mytharc and skip standalone side quests.

14%
86%
Mytharc (3): Crucial lore & season climaxes
Core (19): Character development & subplots
Side Quest (0): Standalone / filler
S20·E1 Mytharc

Arc of Infinity (1)

Jan 3, 1983 · 25 min

On Gallifrey, someone on the high council is perpetrating a treasonous act - transmitting the Doctor's bio-extract from the space/time matrix to an anti-matter being. On Earth, two

S20·E2 Core

Arc of Infinity (2)

Jan 5, 1983 · 25 min

With an anti-matter being trying to enter the universe through the Doctor, risking the destruction of everything, there is only one clear course of action for the High Council of T

S20·E3 Core

Arc of Infinity (3)

Jan 11, 1983 · 25 min

Something seemed amiss about the Doctor's execution, so the Castellan has Commander Maxil discreetly but fully look it. Meanwhile, as the Doctor meets the anti-matter being inside

S20·E4 Core

Arc of Infinity (4)

Jan 12, 1983 · 25 min

The High Council creates a distraction so the Doctor and Nyssa can find Omega on Earth and prevent his reentry into our universe.

S20·E5 Core

Snakedance (1)

Jan 18, 1983 · 25 min

Tegan steers the TARDIS to the planet Manussa, without meaning to - but why? And is it a coincidence that the planet is about to celebrate the 500th anniversary of the expulsion of

S20·E6 Core

Snakedance (2)

Jan 19, 1983 · 25 min

The Doctor talks to Ambril and Chela to try and stop the 500th anniversary celebrations. A possessed Tegan finds herself in Dugdale's Hall of Mirrors to where she summons Lon. The

S20·E7 Core

Snakedance (3)

Jan 25, 1983 · 25 min

The possessed Tegan and Lon try to find the whereabouts of the Great Crystal. The Doctor finds himself in prison, with only Nyssa to try and get him out. Chela tells the Doctor tal

S20·E8 Core

Snakedance (4)

Jan 26, 1983 · 25 min

The Doctor and the original snakedancer Dojjen work to rid the planet of the Mara.

S20·E9 Core

Mawdryn Undead (1)

Feb 1, 1983 · 25 min

The Doctor discovers a starship trapped in a time warp over Earth. Meanwhile, public schoolboy - and secret alien émigré, Turlough, learns he can have that which he most desires, i

S20·E10 Core

Mawdryn Undead (2)

Feb 2, 1983 · 25 min

The TARDIS lands on Earth six years out of date, stranding the Doctor in 1983 while leaving Tegan and Nyssa to look for him in 1977. Both parties also encounter former companion, B

S20·E11 Core

Mawdryn Undead (3)

Feb 8, 1983 · 25 min

Mawdryn and his eternal mutants reveal the truth: they are exiles, they are in pain and need the Doctor's future 'lives', as afforded by each of his remaining regenerations.

S20·E12 Core

Mawdryn Undead (4)

Feb 9, 1983 · 25 min

As the Doctor's ethics are challenged and the two Brigadiers finally meet, Turlough plots with the Black Guardian to bring the Time Lord down once and for all...

S20·E13 Core

Terminus (1)

Feb 15, 1983 · 25 min

Deep space, some time in the future. Still following the Black Guardian's orders, Turlough sabotages the TARDIS, forcing an emergency fusion with an apparently deserted starship. B

S20·E14 Core

Terminus (2)

Feb 16, 1983 · 25 min

The Doctor's party remains divided and scattered as the immense transport docks at the Terminus space station, which turns out to be a leper colony at the exact centre of the known

S20·E15 Core

Terminus (3)

Feb 22, 1983 · 25 min

Since the Doctor's party represents neither lazars nor handlers, they're presumed to be investigators, which is enough to spark the disgruntled Valgard into challenging Eirak over

S20·E16 Core

Terminus (4)

Feb 23, 1983 · 25 min

In attempting to reopen a doorway into the TARDIS, Turlough activates Terminus' automated fuel-jettisoning sequence. The first time this sequence was engaged, it flung its first of

S20·E17 Core

Enlightenment (1)

Mar 1, 1983 · 25 min

After receiving a warning from the White Guardian, the Doctor initially believes the TARDIS has landed aboard an Edwardian clipper ship - but all is not as it seems. While the time

S20·E18 Core

Enlightenment (2)

Mar 2, 1983 · 25 min

Captain Striker and his officers reveal themselves to be Eternals, mind-reading creatures who live outside of time and who require Ephemerals (humans and other "time dwellers") to

S20·E19 Core

Enlightenment (3)

Mar 8, 1983 · 25 min

Turlough's panic puts him aboard a pirate ship where Captain Wrack uses his presence to invite all the other captains over for dinner. She's been picking off a few of her greatest

S20·E20 Core

Enlightenment (4)

Mar 9, 1983 · 25 min

Tegan isn't aware she been outfitted with a device to destroy Captain Striker's ship. While the detonation will merely slip the indestructible Eternals back into the realm of etern

S20·E21 Mytharc

The King's Demons (1)

Mar 15, 1983 · 25 min

In 1215 at the castle of Ranulf Fitzwilliam, son Hugh is jousting on a matter of honor against Sir Gillis Estram, the champion of King John, when the TARDIS appears. The Doctor, Tu

S20·E22 Mytharc

The King's Demons (2)

Mar 16, 1983 · 25 min

England, 1215. With the historic signing of the Magna Carta supposedly only days away, the Doctor is startled to find King John apparently intent on provoking civil war - and seemi

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