The TARDIS Lands in the Swamp
The TARDIS arrives on the third moon of Delta Magna and The Doctor and Romana are forced to leave K9 behind as it soon realised that the ground is very marshy and so unsuitable for K9 to navigate.
Shortly after leaving the TARDIS, and while using the tracer to get an accurate reading for the fifth and penultimate segment of The Key to Time, The Doctor is shot at by two men, Fenner and Thawn, who are from a nearby methane catalysing refinery, while Romana is captured by a group of green-skinned natives, called Swampies.
They soon discover that the Swampies are buying guns from a gun-running human called Rohm-Dutt. Rohm-Dutt is supplying the Swampies guns ostensibly on behalf of an anti-colonial organisation sympathetic to their cause. This however, is part of a plot by Thawn to discredit the pro-Swampie Sons of Earth organisation and open the way for the Swampies to be wiped out.
|Romana and The Doctor in the Reeds
But unknown to Thawn the Swampies intend to attack the refinery the following day and, after capturing Romana, they are now also planning to sacrifice her to their god Kroll that evening.
The Doctor is taken back to the refinery where, hearing the sacrificial drums, he learns from Mensch, a Swampie working at the base, that someone is to be sacrificed. Fearing the worse The Doctor leaves and makes his way towards the Temple of Kroll to rescue Romana. He arrives at the Swampies’ temple just in time to rescue his companion and while making their escape they discover a passageway in the ground, and in it a book which tells of Kroll. Meanwhile the refinery crew notice that the lake bed is shifting, as if there is something massive moving beneath the surface.
|Romana and The Doctor
The Swampies, led by Ranquin, prepare their attack on the refinery but they are stopped in their tracks when an enormous squid-creature appears on the horizon. This is the creature seen moving under the lake bed; it is the Swampies great god Kroll. Kroll starts to attack them while The Doctor, Romana and Rohm-Dutt are captured by the Swampies.
Kroll then heads for the refinery and starts to attack it while The Doctor, Romana and Rohm-Dutt discover that they are sentenced to be sacrificed to the Swampies’ god. They are to be stretched to death by being tied hand and foot to some steadily contracting vines. Fortunately a storm breaks outside and The Doctor manages to shatter the window so that rain enters, slackening the vines and so allowing them to escape.
As they make their way across the swamp, Rohm-Dutt is seized and killed by one of Kroll’s tentacles but The Doctor and Romana manage to reach the refinery. There they discover that Thawn is planning to kill Kroll by aiming an orbital plasma rocket at the creature - the rockets are normally used to seed the moon’s atmosphere thus producing more methane.
Horrified at this course of action The Doctor and Romana go to the rocket silo where The Doctor is able to disable the missile. This though angers Thawn, who takes The Doctor and Romana prisoner once more. But then the Swampies launch their attack on the refinery, killing Thawn.
Kroll then returns to attack the refinery once again. It is then that The Doctor realises that Kroll must have ingested the fifth segment disguised as a Swampie relic, and that it was the segment which was responsible for Kroll growing to such mammoth proportions.
Armed only with the tracer The Doctor goes outside and when he points the tracer at the Kroll the huge creature is transformed into the fifth segment so ending the threat on the refinery.
Having converted Kroll into the fifth segment The Doctor and Romana head back towards the TARDIS with another segment of The Key to Time in their possession.. On there way they discover that in place of the giant Kroll there are countless smaller creatures left lying in the marshes.