S13E15
Gritty, defiant, quietly tragic
Written by Terry Nation
View Graph

The Android Invasion Part 3

The Doctor and Sarah must stop the Kraals' plan to invade Earth using androids and a deadly virus, while also preventing the destruction of a simulated English village.

The Doctor and Sarah find themselves on a Kraal spaceship where they discover the alien's plan to invade Earth. The Kraals have created androids that will take over key positions on Earth, allowing them to assume control without a fight. The Doctor and Sarah also learn about a deadly virus that will be used to eradicate humanity. As they try to find a way to escape and warn Earth, they must navigate the Kraal ship, avoid detection, and prevent the impending invasion. The Doctor and Sarah manage to escape from their cell and make their way to the ship's brig, where they continue to unravel the Kraals' plan. With time running out, they devise a plan to sabotage the Kraal's operation and prevent the invasion.


Events in This Episode

The narrative beats that drive the story

24
Act 1

The narrative opens with the Doctor on the run through a simulated woodland, pursued by an android duplicate of Sarah. Concurrently, aboard a Kraal ship, commanders Styggron and Marshal Chedaki discuss their meticulously planned invasion of Earth. Their strategy involves a deadly virus designed to eradicate humanity and the imminent destruction of the very English village the Doctor is currently navigating, which serves as a training ground for their android forces. The real Sarah, held captive elsewhere on the ship, awakens and overhears the critical "nine minutes" countdown to the village's annihilation. This urgent revelation propels her into action. She races to the village, where she discovers the Doctor captured by Styggron, tied to a village cross, with a matter-dissolving bomb activated at his feet. Displaying quick thinking, Sarah employs the sonic screwdriver to sever the artificial ivy binding the Doctor, freeing him mere moments before the simulated village evaporates in a powerful shockwave. Their narrow escape, however, is short-lived. Upon re-entering the Kraal ship through a hatchway, they are immediately apprehended by Crayford and Kraal soldiers, leading to their swift confinement in a brig. This initial act establishes the immediate, high-stakes threat, the Kraals' advanced technology and ruthless efficiency, and the Doctor and Sarah's precarious situation, culminating in their recapture after a brief, hard-won reprieve.

Act 2

Confined in the Kraal brig, the Doctor systematically deduces their true predicament: they are not on Earth, but aboard a Kraal ship, and all the "humans" they encountered are sophisticated android duplicates. He explains the high radiation levels indicate they are near the Kraal home planet, Oseidon, and the Kraals' desperate plan to abandon their dying world for Earth. Crayford then enters, revealing his deep-seated betrayal of humanity. He recounts how the Kraals saved and reconstructed him after Earth abandoned him in space, and details their meticulously planned invasion: androids will infiltrate key Earth positions, paving the way for Marshal Chedaki's fleet, supposedly without violence. Meanwhile, Styggron finalizes preparations for a deadly virus, instructing an android Harry to deliver poisoned water to the brig. Harry then escorts the Doctor to Styggron's lab for a forced memory extraction. Back in the brig, Sarah, realizing the water is poisoned, ingeniously uses it with a power cable to incapacitate the android guard, Adams, making her escape.

Act 3

Having ingeniously escaped the brig, Sarah races through the Kraal ship's corridors, her path leading directly to Styggron's lab. There, she finds the Doctor strapped to a mind analyser, his brain tissue dangerously over-stimulated and on the verge of bursting, a fate Styggron cruelly elaborated upon before his departure. Styggron, in a moment of chilling candor, revealed the Kraals' true genocidal intent: a highly potent virus designed to eradicate humanity within three weeks, after which it would burn itself out, leaving Earth pristine for Kraal colonization. Styggron himself planned to remain in quarantine aboard Crayford's rocket during this period. Sarah intervenes just in the nick of time, deactivating the analyser and freeing the disoriented Doctor, who struggles to regain his faculties. As Marshal Chedaki's voice echoes through the ship, announcing a mere minute until the invasion rocket's launch, the Doctor, now clearer-headed, identifies Crayford's rocket as their only viable means of escape and their last chance to warn Earth. They embark on a desperate sprint through the Kraal vessel, evading detection amidst the pre-launch chaos, and manage to board the rocket's hold. Inside, they discover pods containing the androids destined for Earth, a grim testament to the Kraals' advanced infiltration strategy. The act concludes with the rocket's final countdown, leaving their fate and the success of the impending invasion hanging precariously in the balance, a dramatic cliffhanger.