Dethras (audio story)

 was the fourth story in the sixth series of The Fourth Doctor Adventures, produced by Big Finish Productions. It was written by Adrian Poynton and featured Tom Baker as the Fourth Doctor and Lalla Ward as Romana II.

Publisher's summary
In the control room of a World War 2 submarine something strange has started to happen. As the ship runs out of control, its crew begin to fall unconscious...

Finding the submarine in the last place they'd have expected, the Doctor and Romana are confronted by a mystery. Once fully populated, there are now only three men on board. And there's now also a chimpanzee.

What has happened to the rest of the crew? What are the strange noises they can hear outside the hull?

And most importantly, who, or what, is Dethras?

Part one
Applying the randomizer for the first time in several journeys, the TARDIS lands on a stricken WWII British submarine. On board are three naval soldiers, John, Philip and Robert, along with a chimpanzee called Franklin.

The panicked crew reveal they have no idea how Franklin got on board, and the sub is near to collapse, but not because it has sunk to the bottom of the ocean. The submarine is adrift in space, just one more vessel in a vast spaceship graveyard orbiting a desolate planet!

The crew members start to display strange abilities - knowledge unknown to twentieth century humans - while Franklin begins to show signs of developing speech.

Meanwhile, on a spaceship elsewhere, Commander Flague is leading a mission to locate a criminal named Dethras...

The submarine is attacked by creatures living in the vacuum of space. They gain access to the sub, ripping open the hold where the TARDIS landed, expelling the police box into the void.

Crewmen Robert and Philip start to mutate into the space creatures. The Doctor amplifies the submarine's primitive comms system, which activates the closest working transmat among the spaceships outside.

The Doctor and John are transported to a nearby, derelict ship - but Romana and Franklin are transported to the warship captained by Commander Flague.

The Doctor confronts John, suspecting he isn't who he claims to be. John acquiesces, revealing he is none other than Dethras!

Part two
Flague opens communications with the Doctor and Dethras, threatening to kill Romana and Franklin unless Dethras is handed over to her.

Dethras and Flague are both members of the Xankari, a race of human-like aliens. Dethras is one of the galaxy's foremost evolutionarily scientists. He sold Flague, a ruthless war-monger, the funding rights to his research into creating a race of super-soldiers able to rapidly evolve to befit any situation or environment.

When Dethras discovered his latest test subjects were innocent submariners kidnapped from the backwater planet Earth, he smuggled them and their sub, along with a chimpanzee test subject, onto a cargo ship.

Piloting the cargo ship to the spaceship graveyard, he planned to set the sub adrift, allowing the humans to die a peaceful death, while he himself went on the run in an effort to keep the secret to his experiment from Flague.

Before he could complete his mission, a meteroid struck the cargo ship, exposing the human test subjects to the vacuum. When they began to mutate into the space creatures, Dethras managed to seal himself, Franklin, Philip and Robert on the sub before the cargo ship disintegrated, leading up to the arrival of the Doctor and Romana...

The Doctor allows the space creatures to attack his and Dethras' ship. Then, he transports the now fully mutated Philip and Robert over from the sub.

Using his own latent Time Lord abilities alongside the hyper-evolutionary abilities of Robert and Philip, he convinces the creatures to telepathically create a grand illusion in the mind of Flague. Flague is led to believe that the outcome of her mission is the destruction of the Doctor and Dethras' ship, along with all the super-soldier creatures from Dethras' experiment, and the execution of Romana and Franklin.

Grimly satisfied at her supposed pyrrhic victory, Flague and her warship departs.

The Doctor and Romana transport the submarine crew to a remote planet where their evolutionary powers will remain stable. Dethras remains with them, aiming to provide care to his former test subjects. Franklin, having now mastered human speech, departs on his own to explore the universe.

Cast

 * The Doctor - Tom Baker
 * Romana - Lalla Ward
 * John - Alistair Petrie
 * Flague - Sheila Ruskin
 * Philip - Josh Bolt
 * Robert - Brian Vernel
 * Franklin - John Banks
 * Xankari / Teacher - Jane Slavin

Continuity

 * The Doctor has been bypassing the randomiser for a few journeys. (AUDIO: The Beast of Kravenos, The Eternal Battle, The Silent Scream)
 * Romana states the Black Guardian is bound to find them again. (PROSE: The Well-Mannered War, AUDIO: Casualties of Time)
 * The Doctor uses his etheric beam locator. (TV: Genesis of the Daleks)
 * Time Lords can survive for a short time in the vacuum of space. (TV: Four to Doomsday)
 * The Sixth Doctor will later encounter Voord that quick-evolve themselves into Cybermen. (COMIC: The World Shapers)
 * The Doctor still wishes to go to Brighton to visit the sea-side. (TV: The Leisure Hive)