Romana Inside the TARDIS

The Prion planetary system contains two habitable planets which have supported civilisations: Zolfa-Thura, a desert world devoid of life bar five giant screens; and Tigella, a jungle seemingly world inhabited by the humanoid, white haired Tigellans.

But the inhabitants of Tigella have a problem: their power source - a mysterious giant dodecahedron - which has powered their underground city since it fell to their planet is now failing. The Tigellans believe that unless they can find a solution to the power loss they are doomed. The race however, is split into two factions: the Savants, led by Deedrix, are scientists who believe that the dodecahedron is an artefact which was manufactured, and the Deons, led by Lexa, are religious worshippers who believe it to be a gift from their god Ti.

The Tigellans’ weary leader, Zastor, has become concerned about the disputes between his people’s two opposing factions. Being an old friend of The Doctor, Zastor invites The Doctor to visit the planet and help investigate what is causing their power source to start fluctuating.

Lexa

Having received Zastor’s summons The Doctor, Romana and K9 try to land the TARDIS on Tigella but someone intervenes, trapping them in a time bubble known as a chronic hysteresis, causing them to repeat their words and actions over and over again.

The TARDIS has been intercepted by the megalomaniac Meglos, the last survivor of Zolfa-Thura, whose race built the dodecahedron. The Doctor and Romana eventually manage to free the TARDIS and so are able to continue their journey to Tigella.

Zastor

Meanwhile Meglos, whose true form is that of a xerophyte, has summoned help in the form of an unruly band of Gaztak mercenaries, led by General Grugger. They kidnap a human and then Meglos, using the body of the kidnapped Earthling, transforms himself into a duplicate of The Doctor. Posing as The Doctor, Meglos then arrives on Tigella and tricks the Tigellans into allowing him access to the dodecahedron. However, when he is alone, he miniaturises the dodecahedron and absconds with it.

The Doctor and Romana finally manage to break the TARDIS out of the time bubble, by throwing it out of phase, and they materialise on Tigella – but in the middle of the hostile jungle rather than near the city. As The Doctor heads off to find Zastor, Romana stumbles across the dangerous vegetation – deadly bell plants – and then the Gaztak mercenaries.

When The Doctor finally meets the Tigellans he is of course accused of stealing the dodecahedron. However, The Doctor manages to escape and, with Romana and K9, follows Meglos back to Zolfa-Thura where the cactus creature reveals his race perished in a civil war over the control of the crystal, which can power a weapon strong enough to destroy planets and that he plans to use the dodecahedron to power an apocalyptic device with which he intends to destroy Tigella.

Romana and The Doctor Exit the TARDIS

The Doctor, although at first hindered by the activities of the group of Gaztak mercenaries, is able to use a little impersonation and fools them into believing that he is Meglos. This allows The Doctor to change the settings of the super-weapon.

After Meglos resorts back into a cactus, so abandoning the Earthling, The Doctor rushes back to the TARDIS, taking the Earthling with him. Meglos is unable to stop him nor is he able to persuade General Grugger not to fire the weapon. From the safety of the TARDIS, The Doctor and his friends witness the destruction of Zolfa-Thura along with the Gaztaks, Meglos and the Dodecahedron.

With Meglos destroyed, the Tigellans are left with the task of rebuilding their lives by reclaiming their planet’s surface from the vegetation now they no longer have the help of the dodecahedron.

As The Doctor and Romana prepare to take the Earthling home, The Doctor claiming that he can get him home before he left, Romana receives a message from the Time Lords stating that she must return to Gallifrey…