An Unhappy Romana

Unbeknown to The Doctor and Romana, who are heading back to Gallifrey so as to return Romana to the High Council of Time Lords, the TARDIS falls through a Charged Vacuum Emboitment, a hole in the fabric of space, and is drawn into E-Space, a smaller universe which coexists with our own.

The first planet The Doctor and Romana arrive on is Alzarius, a seemingly idyllic world of flora and fauna supporting a small but sustainable civilisation of happy and contented people.

The Terradonians are however, misplaced from their own world as according to their records their spaceship, known as the Starliner, crashed on Alzarius fifty years before. They now live on Alzarius, whilst the entire time making repairs to their spaceship in readiness to leave.

K9 at the Console

The colony is run by three self-selecting senior colonists knows as Deciders who ensure the smooth running and order of their adopted world and lay particular store on technical ability. One of the brightest of the younger generation of colonists is Adric, who bears a Badge of Mathematical Excellence in recognition of his computational skills. However, Adric has joined his brother Varsh, along with a number of young Terradonians who have rejected the regimented society of the Starliner. Called Outlers they steal harvested river fruit and other foods to survive.

The arrival of the TARDIS on Alzarius coincides with Mistfall, a periodic event spoken about in the Terradonians’ history, when a race of misshapen monsters, known as Marshmen, emerge from the misty marshes to attack the colony. Also the normally harmless river-fruit The Terradonians harvest hatch venomous spiders.

K9 and The Doctor on Alzarius

As the Marshmen arise and begin to advance on the colony the Deciders evacuate everyone back to the Starliner safe in the knowledge that the Marshmen will not be are able to gain access to the spaceship. The Doctor, however, gains entry to the Starliner, using his sonic screwdriver, but he is followed by a young and inquisitive Marshchild. Both are found and taken before the Three Deciders. The Doctor is appalled when the Terradonians’ chief scientist announces that he intends to perform a vivisection experiment on the Marshchild.

Unable to stop him The Doctor instead works out the truth about the planet and the Terradonians. He realises that all the Terradonians died when they first arrived, and the people who now think of themselves as Terradonians are in fact evolved Marshmen. Mistfall is just a part of the planet’s ecological process, and that the Starliner has been maintained for 40,000 generations by a species that has three aspects; spiders, Marshmen, and the current humanoids. They are all from the same DNA and thus have come "full circle" - the spiders will become new Marshmen and the Marshmen currently attacking the spaceship will eventually evolve into the humanoids who now run the Starliner.

The Doctor also further deduces that the Starliner has been ready for take off for years; the problem is that none of the Deciders will face up to the awful knowledge that they simply don’t know how to pilot the spaceship.

Adric

Meanwhile Romana and K9 venture outside but soon find themselves trapped inside a nearby cave containing the river fruit and also some venomous marsh spiders. As one of the spiders scuttle toward Romana she picks up a river fruit, so as to use it to defend herself. But instead the fruit splits open and another marsh spider emerges. It lands on her cheek and even though Romana tries to fend it off the spider bites her. Almost immediately Romana falls to the ground, unconscious. When she awakes she assists the Marshmen, by opening an emergency escape hatch, to allow the Marshmen to board the Starliner.

Realising that Romana has been infected The Doctor uses a protein serum to cure her. With the Marshmen roaming the Starliner The Doctor realises that they are more inquisitive then dangerous.

When it is accidentally deduced that the Marshmen can’t cope with pure oxygen this non-lethal defence is used to force the Marshmen out of the Starliner. With the Marshmen returning to the swamps The Doctor helps the humanoid Alzarians leave the planet.

The Doctor, Romana and K9 then return to the TARDIS. But as they depart they are unaware that Adric, rather than leave with his own people, has stowed away aboard the TARDIS.