Fabula
S12E18 · Revenge of the Cybermen Part 2

Doctor exposes Cyberman poison in gold discovery

The Doctor reveals the lethal effect of gold on Cybermen, providing Stevenson and Lester with crucial intelligence to combat Vorus’s forces. Kellman’s feigned ignorance of the pentalium drive shatters trust, revealing him as a traitor while Sarah and Harry’s transmat to Voga leaves them vulnerable in the mines. Simultaneously, Cybermen detect the unauthorized use of the transmat beam, accelerating their counterattack and forcing all parties into a race against time to recapture Sarah and Harry before the Cybermen dock with the beacon.

Plot Beats

The narrative micro-steps within this event

2

The Doctor explains to Stevenson and Lester that gold is lethal to Cybermen, revealing a crucial weakness and the reason behind the Cybermen's hatred for the Planet of Gold.

information to concern ['Control Room']

Kellman's betrayal is confirmed as he denies knowledge of the pentalium drive, leading to increased tension and suspicion among the Doctor and his allies.

suspicion to confirmation ['Control Room']

Who Was There

Characters present in this moment

7

Focused determination masked by outwardly measured speech, betraying underlying urgency to rescue Sarah and Harry before the Cybermen exploit the transmat detection. "goals_at_event": ["expose Kellman’s betrayal to save the escape capability

The Doctor strides into the secondary control room as the senior officer and immediately seizes control of the conversation with calm authority, explaining how gold disrupts Cybermen physiology before directly interrogating Kellman about the missing pentalium drive and exposing his hidden spy device. His hands work quickly to dismantle the evidence while his sharp gaze locks onto the traitor.

Character traits
commanding presence quick analytical mind sharp interrogation technique methodical dismantling of evidence moral urgency
Follow The Fourth …'s journey

Determined and focused, viewing the human transmat as both a provocation and an opportunity to advance assimilation objectives. "goals_at_event": ["seize control of the beacon before the transmat energy dissipates

Onboard the Cybership, the Commander receives the transmat beam detection data and immediately orders the boarding party to readiness, demonstrating the Cybermen’s relentless operational calculus and ability to synchronize intellect with machine.

Character traits
decisive command presence rapid tactical assessment cold strategic calculation
Follow Cyberman Commander's journey

Feigned calm masking deep anxiety, rapidly shifting to desperate defiance once direct evidence of his treachery is presented, culminating in a sense of futile resistance. "goals_at_event": ["stall for time to let Cybermen reinforcements arrive

Kellman enters a defensive spiral under doctrinaire interrogation, feigning ignorance of the pentalium drive while betraying naked nerves as the Doctor dismantles his spy device in front of Stevenson and Lester; his calm facade disintegrates into flustered denial and then frantic resistance at the moment of exposure.

Character traits
adept liar initially nervous evasiveness under pressure expertise in deception no combat skill
Follow Professor Kellman's journey
Supporting 2

Balances grave concern for Sarah and Harry with growing realization that Kellman’s lie could have cost the station its last lifeline, yielding cautious optimism and motivation to act. "goals_at_event": ["secure immediate clarity on how to counter Cybermen physiology

Stevenson stands at the nerve center of the secondary control room, absorbing the Doctor’s explanation with intense curiosity before asking for clarification on gold’s deadly effect; he listens as betrayal unfolds but remains physically poised rather than impulsive, framing a rare moment of grateful receptiveness toward alien counsel.

Character traits
attentive listener crisis-trained reflexes command presence grounded in protocol tactical curiosity
Follow Commander Stevenson's journey

Impersonal aggression, driven entirely by institutional orders rather than individual animus, reflecting the Guardians’ role as Vorus’s blunt instruments. "goals_at_event": ["remove perceived threats from critical areas

The Vogan Guards appear without warning from dim tunnels, seizing Sarah and Harry with brute efficiency and shoving them aboard a utilitarian trolley car; their actions are silent and authoritative, leaving no room for negotiation while enforcing Vorus’s punitive mandate in the mines.

Character traits
ruthlessly efficient suppressors silent but forceful presence faithful enforcement of Vorus’s orders
Follow Voga Enforcement …'s journey
Sarah Jane Smith

Sarah struggles against the Vogan guards’ iron grip, loudly protesting their treatment and insisting the guards are overreacting to a …

Lester Riggs

Harry calmly attempts to reason with the same Vogan guards, engaging in measured dialogue to defuse the situation while being …

Objects Involved

Significant items in this scene

2
Kellman's Hidden Spy Device (Cyberman Uplink & Power Unit)

The hidden spy device found in Kellman’s cabin is dismantled by the Doctor in front of Stevenson and Lester to reveal its sophisticated circuits whose sole purpose was clandestine communication with the Cybermen, exposing Kellman’s dual allegiance. "status_before_event": Concealed inside Kellman’s private quarters, operational and interfacing with Cyberman command channels. "status_after_event": Partially disassembled in the secondary control room; Kellman’s attempts to defend it collapse into transparent shame as the Doctor’s demonstration strips away his deception.

Pentalium Drive (Transmat System Component)

The pentalium drive is missing from the transmat console in the secondary control room; its absence is highlighted by the Doctor as a direct reason the rescue transmat cannot be reactivated, tying Kellman’s sabotage to the immediate danger facing Sarah and Harry down in the mines.

Before: Installed component critical to transmat function, present during …
Before: Installed component critical to transmat function, present during normal station operations. "status_after_event": Removed and secreted by Kellman as part of his sabotage plan, leaving the system crippled and the Doctor scrambling for alternatives.

Narrative Connections

How this event relates to others in the story

What led here 3
Causal medium

"The Doctor's accusation tying Kellman to the Cybermen is directly tied to his later explanation that gold is lethal to Cybermen, suggesting the sabotage was part of a Cyberman plan to neutralize gold's threat on Voga."

Doctor uncovers sabotage during desperate rescue
S12E18 · Revenge of the Cybermen Part …

"Kellman's betrayal as revealed in the interrogation is confirmed when he denies knowledge of the drive but later surrenders under threat from a cybermat—showing his consistent pattern of secret dealings and forced complicity."

Cybermat venom forces emergency transmat
S12E18 · Revenge of the Cybermen Part …

"Kellman's betrayal as revealed in the interrogation is confirmed when he denies knowledge of the drive but later surrenders under threat from a cybermat—showing his consistent pattern of secret dealings and forced complicity."

Doctor uncovers sabotage loses Sarah
S12E18 · Revenge of the Cybermen Part …
What this causes 2

"The gold shackles that bind Sarah and Harry symbolize the very element that poisons the Cybermen—showing that the Vogans’ wealth, though protective, also traps and restrains, much like Vogan society itself."

Harry and Sarah escape shackles with gold filing
S12E18 · Revenge of the Cybermen Part …

"The Doctor’s revelation that gold is lethal to Cybermen is mirrored in Tyram’s body on a slab in Vogan society—both representing a society where survival is predicated on weaponizing their environment (gold or blades), just as the Cybermen pervert technology."

Tyram strips Vorus of mine control
S12E18 · Revenge of the Cybermen Part …

Key Dialogue

"DOCTOR: Voga, otherwise known as the Planet of Gold, is hated and feared by Cybermen because gold is lethal to them."
"STEVENSON: How?"
"DOCTOR: It's the perfect non-corrodible metal. It plates their breathing apparatus and in effect suffocates them."