Doctor Who (1963) Season 18 Episode 10 Full Circle (2)

The Doctor and his companions, Romana and K-9, materialize on the planet Alzarius, a verdant world suspended in space outside the known universe. They have arrived during a survey by a team from the spaceship Starliner, which has been trapped in orbit around the planet for centuries. The Alzerians they encounter on the surface of the planet are all clothed in furs, and their leader, Varsh, is hostile. The Doctor also discovers that time moves more slowly on the planet's surface than it does on board the Starliner, due to a relativistic effect.

The Time Lord and Romana are separated from K-9 and the TARDIS when the latter is dragged beneath the surface of a lake by a strange swamp creature. As the Doctor sets out to find the dog, Romana is captured by the Alzerians. However, she is helped to escape by a boy named Adric, who reveals that the Alzerians are not natives, but the descendants of a group of Starliner crewmembers that landed on the planet centuries earlier. Adric's father, Decider Draith, has forbidden the Alzerians from contacting the Starliner, and is actively concealing the fact that the ship can no longer leave the planet.

The Doctor and K-9 discover a cave system that takes them inside the planet's surface, where they find a vivid jungle-like ecosystem with bioluminescent plants and a host of strange creatures, including the swamp creature that took K-9. They soon encounter a group of humanoids who seem to be hostile, but turn out to be the evolved descendants of the Starliner's crewmembers, who have been trapped underground since the ship crashed on the planet. These people are aware of their upcoming evolution, but lack the knowledge to control their changes. The Doctor and K-9 work with the Alzerians to try and help the Starliner reach escape velocity.

Against a ticking time bomb, the Doctor and his companions begin to suspect that the investigation has more to it than the sterile existence of humans trying to escape a planet. They soon encounter another humanoid - a Marshman, who claims to have existed on Alzarius before the humans arrived. The Doctor, suspicious of the Marshman's claims, soon realises that the Marshmen are not native to Alzarius, but originated on the Starliner itself. The Doctor realises too late, that the Marshmen are part of a much greater danger to the crew of the Starliner and the survival of the Doctor himself.

As tensions increase and danger lurks around every corner, the Time Lord must navigate the complex machinations of the evolution process and a rapidly evolving planet that seems to be echoing the sentiments of its inhabitants. Can he discover the real threat before it is too late? Full Circle (2) is a gripping episode with stunning visual effects and intelligent storytelling that will keep audiences on the edge of their seats.