While trapped in E-Space, the Doctor receives a distress signal that prompts him to take the TARDIS to a planet in close orbit to a large sun — too close, in fact, as whichever side of the planet is facing it is totally uninhabitable. In order to survive, the crew of the Tantalus were forced to adapt their ship to run along vast tracks to stay ahead of the fatal sunlight all the way around the planet. While the Doctor obviously wants to help, he soon realises that this is far from simple.
Tropes
- The Assimilator: A rare benevolent example of this, as the hive mind of the planet only makes the offer to bring the remaining crew into itself because there was literally no other way out, and it is made clear that they will retain their individuality and can eventually choose to be ‘dispersed’ if they wish.
- Both Sides Have a Point: While Romana has moral objections to helping the Tantalus crew after learning about Pilot Dena’s methods, Adric argues that they don’t know enough about the situation to judge her.
- Convection, Schmonvection: Defied; the sunlight on this planet is so hot that the Tantalus crew consider it impossible to retrieve the TARDIS even if they literally saw it just moments before it entered the sunlit side of the planet.
- "Could Have Avoided This!" Plot: Invoked at the end when Romana learns that the Doctor set the HADS before he left the TARDIS, with the result that the ship was relocated to a position on the planet’s dark side rather than stuck in the sunlight, although the Doctor argues that after the TARDIS was ‘lost’ in the sunlight he was just focusing on staying alive and didn’t trust Dena with that knowledge.
- Evil Cannot Comprehend Good: Dena may be more ‘insane’ than evil, but her main problem was that she tried to force the TARDIS crew to help her rather than trust that they would help her anyway.
- Generation Ship: The Tantalus has been stuck on this planet for over a century, and the crew are thus the descendants of the original.
- Godzilla Threshold: Eventually, the only way to save any of the crew is for them to accept the offer to become part of the planet’s collective consciousness, essentially dying.
- The Great Repair: In a sense; after the Tantalus crashed, the crew couldn’t repair the engines before the sunlight would have destroyed them, so they adapted it to travel along vast railway tracks so that they could stay ahead of the fatal sunlight.
- Grey-and-Gray Morality: Romana is accused of this when she focuses on saving Adric over any one of the thirty Tantalus crew in the same position as him.
- Healing Factor: Adric’s ability to heal saves him from the spores on the planet, allowing his body to survive the initial release so that his mind can be returned to it.
- Not-So-Well-Intentioned Extremist: Pilot Dena basically wants to keep the crew of the Tantalus alive, but on several occasions she prefers to focus on the simple solution of just killing crewmembers she perceives as surplus to requirements.
- Poor Communication Kills: It’s possible that the Doctor would have been able to save the surviving Tantalus crew if both sides had trusted each other enough for the Doctor to propose the TARDIS as an option earlier.
- Plot-Driven Breakdown: Despite Pilot Dena’s insistence that they keep going, Engineer Terson argues that the engines would inevitably break down even if they did everything right because entropy demonstrates that even the best-maintained engine can’t last forever.
