Ep 4. Spearhead From Space (4)

Doctor Who season 7 episode 4, titled "Spearhead From Space," follows the adventures of the newly regenerated Third Doctor, played by Jon Pertwee. The episode begins with the Doctor stumbling out of the TARDIS and collapsing in a forest. He is discovered by UNIT (Unified Intelligence Taskforce), a government organization tasked with investigating extraterrestrial threats to Earth.

As the Doctor recuperates in a UNIT hospital, strange occurrences begin to happen in the surrounding area. People start appearing to have been frozen in mid-movement, and objects are found that seem to have been melted by an intense heat. Soon, it becomes apparent that aliens have crash-landed on Earth and are using the surrounding woodland as cover for their activities.

The Doctor, with the help of UNIT, investigates the situation and discovers that an invasion is imminent. The aliens are revealed to be Autons, a race of living plastic creatures controlled by a powerful entity known as the Nestene Consciousness. The Autons are able to take on the appearance of any object made of plastic, and they plan to use this ability to infiltrate and take over Earth.

As the Doctor and UNIT attempt to stop the Autons, they discover that there is a traitor within their ranks who is working for the aliens. The traitor is later revealed to be Channing, a high-ranking member of UNIT who has been taken over by the Nestene Consciousness.

In the climax of the episode, the Doctor and UNIT launch a preemptive strike on the Nestene's hiding place, which turns out to be a plastics factory. A tense battle ensues, with both sides suffering heavy casualties. In the end, the Doctor is able to destroy the Nestene Consciousness, causing the Autons to revert back to their plastic form.

The episode concludes with the Doctor and UNIT celebrating their victory, but hinting that more extraterrestrial threats could be on the horizon. Overall, "Spearhead From Space" is a thrilling introduction to the Third Doctor, and sets the stage for a number of iconic Doctor Who stories to come.