Object

Pentalium Drive (Transmat System Component)

Cylindrical component with pentalium circuitry pattern, critical for transmat system functionality and sabotage investigation aboard the Cyberman-controlled space station

6 appearances

Purpose

To supply critical power or signal modulation for the transmat system's activation and stabilization

Significance

The linchpin of Kellman's betrayal, this stolen component triggers the Doctor's transmat to fail just as Sarah and Harry attempt extraction. Its retrieval from Kellman's possession becomes the difference between life and death, forcing the Doctor to bargain with a cybermat to force its surrender. The drive's absence simultaneously disables the rescue beacon and empowers Vorus's Cybermen forces.

Appearances in the Narrative

When this object appears and how it's used

6 moments

S12E18 · Revenge of the Cybermen Part 2

Doctor exposes Cyberman poison in gold discovery

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 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.

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S12E18 · Revenge of the Cybermen Part 2

Cybermen respond to unauthorized transmat to Voga

The pentalium drive is missing from the transmat system in the secondary control room, its absence directly exposed during the Doctor’s dismantling of Kellman’s spy device. The Doctor explicitly connects the sabotage to the drive’s absence, stating that without it, the transmat beam cannot function to rescue Sarah and Harry. This object’s compromised state becomes the critical obstacle just as the Cybermen detect unauthorized energy.

Before: Missing from transmat console, having been removed by Kellman to sabotage rescue capability

After: Still missing; sabotage confirmed and heightened in importance as Cyber threat escalates

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S12E18 · Revenge of the Cybermen Part 2

Stevenson corners Kellman with Cyberman threat

The pentalium drive's location becomes the central point of contention, with Kellman eventually surrendering it after the cybermat's appearance. The Doctor secures it, enabling the plan to rescue Sarah and Harry.

Before: Secreted around Kellman's neck as an incriminating piece of evidence

After: In the Doctor's possession, its absence no longer crippling the transmat system

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S12E18 · Revenge of the Cybermen Part 2

Doctor reclaims pentalium drive using cybermat

The pentalium drive is the focal point of the dispute, with Kellman eventually surrendering it to the Doctor under duress. Its retrieval restores the transmat system’s integrity, enabling the rescue of Sarah and Harry from the secondary control room before the Cybermen overrun the station.

Before: Hidden around Kellman’s neck and smuggled as a mineral analysis tool to obscure its true purpose and sabotage capability.

After: Taken by the Doctor into possession, functionally validated and reinserted into the transmat system to restore emergency functionality.

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S12E18 · Revenge of the Cybermen Part 2

Doctor uncovers sabotage during desperate rescue

The pentalium drive, absent from the transmat system, is identified by the Doctor as the specific component sabotaged to disable the beam. Its removal prevents calibration of the transmat beam, forcing the Doctor to realize that communication and rescue routes to Voga have been deliberately severed as part of a larger plot.

Before: Originally installed and functional in the transmat system; Kellman had previously removed it as part of his betrayal.

After: Confirmed missing and exposed as the cause of the transmat failure, becoming a critical piece of forensic evidence in the investigation of sabotage.

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S12E18 · Revenge of the Cybermen Part 2

Sarah and Harry forced into custody

The pentalium drive, when missing from its slot in the transmat system, is discovered by Lester in Kellman’s cabin and presented to the Doctor, who dismantles it to reveal its true function as a covert communication device linking Kellman to the Cybermen.

Before: Hidden by Kellman in his cabin as part of his sabotage plan against the transmat system.

After: Exposed and disassembled, its hidden circuitry laid bare, implicating Kellman and enabling the Doctor to understand the sabotage hindering Sarah and Harry’s rescue.

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