A Dominator and Two Quarks

On an apparently deserted island, on the peaceful planet of Dulkis, two alien and ruthless Dominators have landed in their spaceship. It seems that the senior, Navigator Rago, is at odds with Probationer Toba, making for a very uneasy partnership. The Dominators are aided by their robotic servants, The Quarks, who have been instructed to start drilling bore holes.

Near the island three Dulcians are on an excursion trip. As they approach the island Cully, the organiser of the excursion, tells his passengers that they are about land on The Island of Death - an atomic test site. But his passengers doubt this as the radiation counters show no sign of any radiation. However, as they leave the ship they are attacked by The Quarks and all, except for Cully, are killed. The Quarks then destroy Cully’s ship.

Nearby the TARDIS materialises on the island. The Doctor tells his travelling companions, Jamie McCrimmon and Zoe Heriot, that Dulkis is a quiet and peaceful planet where they can have a holiday. However, shortly after leaving the TARDIS they hear the explosion caused by the destruction of Cully’s ship, and set off to investigate.

The Dominator's Spaceship

On the way The Doctor and his companions discover a ruined war museum which is full of weapons. Then without warning they are taken prisoner by three figures in radiation suits who take them to an observation centre. After it is confirmed that The Doctor and his two companions are not contaminated, their captors reveal themselves to be two Dulcian students and their teacher, Educator Balan, who are on the island studying the effects of the radiation from an atomic explosion, that had been set off as a warning about the use of such weapons, many decades before.

Cully, on his way to the museum observes the two Dominators discussing whether to destroy the recently discovered TARDIS. The headstrong Toba wants to blow it up but Rago orders that they must conserve their dwindling energy supplies. On arriving at the museum Cully warns Balan and The Doctor about the aliens and their talk of destroying the TARDIS. The Doctor and Jamie rush to check the time machine while Balan contacts the Dulcian capital. The Dulcian leaders order that Zoe and Cully should travel to the capital by transit capsule. Within minutes they arrive in the capital and are taken before the council. Zoe is shocked to discover that the Dulcian Councillors start to debate every point no matter how trivial. It also becomes apparent that being pacifists they also disbelieve that their planet has been invaded. Realising they are getting nowhere, as they have no proof about The Dominators arrival, Zoe and Cully steal a transit capsule so that they can return to the island.

Leaving the TARDIS

The Doctor and Jamie, meanwhile, find The Dominator's spaceship and are captured. Assuming they are Dulcians, Rago orders them to be tested for strength and intelligence to see whether they are suitable as slaves. The Doctor pretends to be stupid by deliberately failing the tests and they are declared useless and freed. However, while inside The Dominator’s spaceship he learns that The Dominators seem to be attempting to mine some kind of element from the planet. The Doctor and Jamie travel to the capital Unaware that Zoe and Cully are on their way back to the island. The Doctor warns the council about The Dominators but the Dulcian leaders still cannot decide a course of action preferring to do nothing. It is then that The Doctor and Jamie discover that Zoe is no longer in the capital and that it is suspected that she, and Cully, have both returned to the island. As The Doctor and Jamie race back to the island, in a transit capsule, they realise that they are heading straight towards a waiting Quark forcing The Doctor to fly the capsule manually resulting in a heavy but safe landing.

On arrival they discover that The Dominators have discovered the observation centre and have taken Balan, his two students, Zoe and Cully prisoner. They have been set to work clearing the drilling sites so as to conserve the Quarks' energy supplies. However, just before The Doctor and Jamie arrive, Zoe and Cully have already worked out a plan of escape. With Zoe creating a diversion Cully is able to run into the museum and grab a laser gun. However, the plan backfires when he finds that he lacks the courage to use the weapon. Jamie though finds Cully in the museum, takes the gun from the Dulcian and fires it at a Quark. Enraged at the destruction of one of the Quarks, Toba orders the other Quarks to fire on the museum building until it collapses. Luckily for those inside an underground shelter is discovered – so offering them protection from the collapsing building above. Once the museum is destroyed Toba returns to The Dominators spaceship. He is accompanied by The Doctor, who had been captured, Zoe and Balan. Onboard The Dominators spaceship Toba kills Balan and threatens to kill The Doctor but is stopped by Raga who is furious at Toba's continued disobedience and the time and resources that are being wasted. He therefore orders Toba to return to the drill site and insists that there must be no more delays.

It is while back inside The Dominators spaceship that The Doctor discovers that the spaceship is capable of storing vast quantities of radiation to power both the spaceship and the Quarks. He also learns that The Dominators plan to fire rockets into the planet's molten core to weaken it so that they can then drop an atomic seed capsule into the resulting eruption. This will then turn Dulkis into a radioactive mass which will then be used to fuel The Dominators' fleet.

Zoe and Cully

The Doctor and Zoe are able to escape and, on reaching the ruined museum, are reunited with Jamie, Cully and the other Dulcians. Realising what The Dominators are planning to do the Dulcians, with the help of the time travellers, start to dig a horizontal tunnel towards where The Dominators are drilling. The plan is to intercept the seed capsule dropped down the central bore hole and so prevent the planet's destruction.

So as to slow down the drilling process Jamie and Cully use guerrilla tactics to destroy the Quarks so enabling the side tunnel to be completed just in time. With drilling complete and the Quarks running out of energy Rago orders the remaining Quarks to return to the spaceship. The Dominators then start to make preparations to leave before the planet is destroyed. With the seed capsule in his hands The Doctor realises that he is unable to prevent it from exploding. He is though able to return the seed capsule to The Dominators spaceship just before it takes off. So instead of exploding deep under the planet’s surface it explodes within The Dominator’s spaceship destroying the Quarks and killing the two Dominators.

With the planet safe The Doctor and his companions make a hasty return to the TARDIS as lava, the result of a minor volcanic eruption caused by the rockets fired into its magma, flows towards the time machine.