Fabula
Object
Object

Master’s Perspex Hostage Tubes (Jo Grant Imprisonment Device)

Transparent perspex cylinders used to imprison Jo Grant and threaten her with lethal gas, forcing the Doctor’s compliance. Featured in Episodes 19–20 (Colony in Space Parts 5–6), where Caldwell pries them open to free Jo, exposing the Master’s cruelty.
2 appearances

Purpose

Imprison captives inside transparent perspex cylinders and threaten with lethal gas for control.

Significance

Gives the Master leverage over the Doctor by holding Jo Grant hostage, enabling compliance and intelligence manipulation.

Appearances in the Narrative

When this object appears and how it's used

2 moments
S8E19 · Colony In Space Part 5
Master’s Hostage Leverage

The perspex containment tubes are the physical embodiment of the Master’s control, trapping Jo and initially the Doctor in transparent, inescapable prisons. Jo’s tube, in particular, becomes the focal point of the Master’s threat, its perspex walls a fragile barrier between her and the lethal gas that could fill it at any moment. The tubes are not just containers; they are symbols of the Master’s power to confine and manipulate, reducing his captives to helpless pawns in his game. The Doctor’s release from his tube is a hollow victory, as his freedom is immediately exchanged for the burden of Jo’s safety.

Before: Both tubes are fully operational, with Jo and the Doctor securely confined within them. The Doctor’s tube is intact, while Jo’s remains sealed and vulnerable to the gas threat.
After: The Doctor’s tube is empty and open, its door ajar, while Jo remains trapped in hers. The Master’s threat ensures the tube’s seal is now a matter of life and death, its perspex walls a fragile barrier against the gas.
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S8E20 · Colony In Space Part 6
Jo Reveals Master’s True Identity

The Master’s perspex containment tube is the physical prison from which Jo is freed, symbolizing both her captivity and the Master’s control over the situation. Caldwell’s struggle to open it highlights the tube’s advanced and unfamiliar technology, while Jo’s collapse upon release underscores the tube’s role as an instrument of suffering. The tube’s transparency adds a layer of psychological torment—Jo is visible but inaccessible, her plight on full display. Its opening marks a shift from confinement to revelation, as Jo’s freedom becomes the catalyst for the Master’s exposure.

Before: Sealed and active, with Jo trapped inside, coughing and disoriented. The tube is fully functional, its perspex walls intact and its locking mechanism engaged.
After: Open and empty, its door pried apart by Caldwell. The tube is now inert, its purpose fulfilled, and it stands as a silent witness to the interrogation that follows.
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