Doctor Who
S20E10
· Mawdryn Undead Part 2

Tegan activates the TARDIS homing beacon under threat

Tegan risks everything to restore the TARDIS homing beacon, sensing something is terribly wrong with the wounded figure masquerading as the Doctor. Her quick diagnosis exposes a deception that could doom them all if unchecked, while committing the team to an immediate escape before the Black Guardian’s influence fully takes hold. The beacon’s activation becomes the first defiant act against an unseen temporal predator, accelerating the crisis at Brendon Public School beyond mere survival into the realm of identity and trust. key_dialogue: [ TEGAN: Spot on. BRIGADIER: One of the Doctor's gadgets? TEGAN: Don't want to miss the Tardis, do we? I've just realised. The Doctor is expecting the Tardis to follow him through to 1983. Don't you see? The wounded thing in the capsule, maybe it isn't the Doctor after all. Come on. ]

Plot Beats

The narrative micro-steps within this event

1

Tegan successfully activates the TARDIS homing device.

hope

Who Was There

Characters present in this moment

2
Tegan Jovanka
primary

Urgently focused with a thread of fear about trusting the wrong 'Doctor', masking deeper dread with sharp authority

Tegan stands tense, gripping the active homing device, her voice clipped with urgency as she pieces together a critical temporal discrepancy. She pivots from observation to action, practically dragging the Brigadier toward escape, eyes scanning for unseen threats while maintaining outward command.

Goals in this moment
  • • Secure safe evacuation for the group by ensuring the TARDIS follows them
  • • Expose the temporal imposter to prevent the Black Guardian from fully corrupting their escape
Active beliefs
  • • The homing device is their only reliable link to survival and true Doctor
  • • Time is collapsing around them—delay equals catastrophe
Character traits
Alert and decisive Analytical under pressure Direct and commanding
Follow Tegan Jovanka's journey
Supporting 1
Brigadier Alistair Lethbridge-Stewart
Brigadier
 secondary

Professionally cautious, subtly unsettled by being out of his depth and by Tegan’s alarm

The Brigadier listens with military caution, his gruff demeanor momentarily stripped of habitual authority as he questions the device’s nature. His limited understanding of the TARDIS technology makes him slow to grasp the implication, but his instinct for protocol surfaces even in amnesiac fog.

Goals in this moment
  • • Determine whether the device is trustworthy and aligns with military protocol
  • • Support Tegan’s urgent directive to avoid endangering the mission further
Active beliefs
  • • The Doctor’s equipment is reliable unless proven otherwise
  • • Obeying orders without delay is his duty
Character traits
Methodical and cautious Grappling with unfamiliar technology Protective in demeanor
Follow Brigadier Alistair …'s journey

Objects Involved

Significant items in this scene

1
Nyssa's Homing Device

The homing device, still active in Tegan’s grasp, becomes the fulcrum of survival: she activates it not just as a navigational tool but as a diagnostic instrument, deducing temporal fraud by recalling the true Doctor’s expected trajectory.

Before: Recently handed to Tegan by Nyssa; accurate function …
After: In use, moving with Tegan toward immediate escape—its …
Before: Recently handed to Tegan by Nyssa; accurate function unknown but presumed operational
After: In use, moving with Tegan toward immediate escape—its signal now triggers the TARDIS to follow

Location Details

Places and their significance in this event

1
Brendon Public School Complex

Brendon Public School, a place of structured youth and jubilee cheer, ironically shelters chaos as Tegan forces a reckoning with identity and time. The narrow classroom, soaked in patriotic celebration below, becomes a pressure chamber where urgent decisions override safety.

Atmosphere Tense anticipation crackling beneath superficial schoolyard festivity, corridors alive with chaotic energy that heightens urgency
Function Crisis staging area where trust is tested and decisions must be made in real time
Symbolism Represents institutional order collapsing under cosmic pressure—a metaphor for human systems failing against time itself
Access Effectively unrestricted at this moment as the school hosts a public event, allowing escape routes …
Echoing schoolchildren’s cheers and slamming doors Sunlight filtering through tall windows casting geometric shadows on worn desks

Narrative Connections

How this event relates to others in the story

What led here 1
Causal

"Nyssa’s giving Tegan the homing device allows Tegan to attempt to return the TARDIS to the correct time, culminating in her successful activation of the device after discovering the temporal discrepancy."

Tegan resolves to flee TARDIS for help
S20E10 · Mawdryn Undead Part 2
What this causes 1
Escalation

"Tegan’s suspicion that the burnt figure is not the Doctor (stated to the Brigadier) escalates into a direct confrontation with Nyssa, where Tegan insists the identity cannot be the Doctor, creating tension among the companions."

Companions question the Doctor's identity
S20E10 · Mawdryn Undead Part 2