The Doctor Keeping Fit

In the courtroom, aboard the Time Lord’s space station, The Doctor’s trial continues. After a short recess to allow a distraught Doctor to come to terms with the recent news of Peri’s death (see "Mindwarp"), The Valeyard rests his case for the prosecution. It is now The Doctor’s turn to present a case for the defence. He chooses an incident from his own future in the hope that by showing the court an adventure from his own future that he can demonstrate that he has mended his ways. The video screen therefore shows The Doctor, now travelling with a young girl named Melanie Bush - a keep-fit fanatic who has him exercising and drinking carrot juice - and their latest adventure begins when the TARDIS picks up a distress call from someone aboard the intergalactic liner Hyperion III.

This space liner ferries between Mogar and Earth in the year 2986, and amongst its present cargo are precious metals from Mogar and a mysterious caged, light-shielded hydroponic section containing several giant vegetable pods. Aboard is a passenger called Grenville who is recognised by one of his fellow travellers, Kimber, as being a man named Hallet. Grenville though dismisses this as a case of mistaken identity, but his actions are suspicious and he later disguises himself as a crew member in order to gain access to the cargo hold.

Arriving on the Hyperion III, The Doctor and Melanie Bush are arrested as intruders. But when they meet Commodore Travers - the officer in charge of the space liner - it is revealed that he is an old acquaintance of The Doctor’s. Commodore Travers though is sceptical of The Doctor’s explanation for his arrival and claims to know nothing of any distress call being sent from the Hyperion III. However, he tells the space liner’s security officer, Rudge, to allow the two travellers the freedom of the passenger quarters so if The Doctor is up to no good, he will soon incriminate himself.

Professor Sarah Lasky

The Doctor and Melanie Bush therefore join the rest of the passengers, who include a group of botanists led by Professor Sarah Lasky. It is they who are responsible for the hydroponic section in the cargo hold, and also for a guarded isolation room which is off-limits to everyone else. It is not long before it is realised that Grenville has disappeared and when The Doctor and Melanie Bush investigate one of his shoes is found by the space liner’s incinerator. The implication is that he has been murdered. The Doctor then suggests that Melanie Bush should investigate the hydroponic section on her own.

In the courtroom the video footage suddenly stops and The Doctor again tells the court that the Matrix is wrong, asserting that this section of evidence was different when he reviewed it earlier. He has a strong feeling that he is being manipulated and that the evidence is being tampered with. Unable to prove this the video footage continues with Melanie Bush being shown around the cargo hold by the space liner’s communications officer, Edwardes. But, to her horror, he is electrocuted when he touches a metal grille surrounding the hydroponic section. The electrical discharge also causes the creatures within the pods to start moving and ultimately to break out. A guard who arrives to investigate Edwardes’ death, having been alerted by Melanie Bush, is also killed by the creatures.

Commodore Travers

Also aboard the Hyperion III are three Mogarians, natives of Mogar who have to wear special breathing apparatus to survive in the same atmosphere as humans as oxygen is poisonous to them. They berate Commodore Travers for steering the space liner too close to a black hole, and also complain about Earth’s mining of Mogar for metal. One of the Mogarians later turns out to be Grenville/Hallet in disguise. He is an undercover agent, an old friend of The Doctor’s, and was responsible for sending the distress signal to the TARDIS. However, before he can reveal his reasons for doing so he is poisoned. Meanwhile in the hydroponic section Professor Lasky, and her assistants, try to cover up the fact that the pods in their charge are now empty. The Doctor and Melanie Bush, however, are highly suspicious of Professor Lasky and trick their way into the guarded isolation room. There they find Ruth Baxter, another of the Professor’s assistants, who is slowly turning into a mutant form of plant life.

Melanie Bush manages to record on tape some alien voices which she has overheard plotting the destruction of all animal-kind. The tape though is subsequently stolen, however, and she suspects that the culprit could have been the space liner’s stewardess, Janet. Therefore at The Doctor’s suggestion, she goes to search Janet’s cabin. The Doctor then makes for the liner’s communications room where he smashes the equipment with an axe. However, back in the courtroom the video footage again suddenly stops with The Doctor protesting once again that this is not what really happened.

Back aboard the Hyperion III, while Melanie Bush is in Janet’s room, it is entered and wrecked by one of the alien plant-creatures, or Vervoids. At the same time Bruchner, another member of Professor Lasky’s team, is plotting to destroy them, having realised the threat that they pose to the human race. The Vervoids on realising this are determined that he should be the next to die. After burning the team’s notes, Bruchner obtains a gun and heads for the flight deck. He manages to set the space liner on a suicide course for the Black Hole of Tartarus before succumbing to a cloud of poisonous marsh gas emitted by a Vervoid in the air conditioning duct. The presence of the gas prevents the space liner’s human crew from entering the flight deck to alter course, but Rudge summons the two Mogarians, Atza and Ortezo, who can do so without suffering any ill effects.

Rudge

However, it transpires that Rudge and the Mogarians have been planning all along to hijack the space liner and now that they have seized control of it, they refuse to hand it back to Commodore Travers. The Mogarians are angry about the human exploitation of their home planet, while Rudge is in it simply for the money - this being his last tour of duty. The Mogarians’ plan goes awry, however, when an unseen figure enters the flight deck and throws acid on their face masks, allowing the space liner’s air to penetrate and suffocate them. With his allies dead, Rudge is easily overpowered.

The Vervoids then begin a reign of terror on the space liner, systematically wiping out the human crew and passengers. Another of Professor Lasky’s assistants, Doland, is also revealed to be behind the murder of Hallet and the Mogarians. He plans to bring the Vervoids to Earth, for use as cheap slave labour. However, he too is killed by the creatures. The Doctor realises that the space liner’s occupants are in a terminal situation: it is a case of kill or be killed. When Commodore Travers also realises this he asks The Doctor for his help - so allowing The Doctor in the courtroom to point out that this proves his assistance was requested. He was not interfering.

Back aboard the Hyperion III The Doctor realises that rather than try to kill the Vervoids, it would be better to encourage them to grow. In the cargo hold is a metal called Vionesium, which has properties similar to those of magnesium and emits a bright light when exposed to air. The Doctor instructs Commodore Travers to switch off all the lights on the space liner. This causes the Vervoids to return to their lair, where The Doctor and Melanie Bush use Vionesium bombs to expose them to intense light. This causes the creatures’ growth to accelerate out of control and they all turn brown and crumble to dust as all their energy reserves are used up.

In the Time Lord courtroom, when questioned, The Doctor is forced to admit that his actions on board the Hyperion III resulted in the deaths of all the Vervoids. He however, justifies this by arguing that if even one leaf had survived, and reached Earth, then it would have meant the end of the whole human race. Seizing on this, The Valeyard accuses The Doctor of destroying an entire species and asserts that the charge against him must again change. The Inquisitor agrees that Article 7 of Gallifreyan Law can be invoked. A shocked Doctor now stands accused of genocide…