The Doctor and Tegan are trying to take the Gravis to a new planet, but the planet on which they have landed isn't the right one. The Doctor wants to explore, and the Gravis is willing (at first) but Tegan isn't interested in this wet, muddy planet.
Suddenly the trio is attacked by several armadillo-like creatures with guns. They plan to execute the Doctor to prevent him interfering with their great plan. The creatures, who are Queeth, don't seem to be able to hit them, and the Doctor is able to talk them out of their weapons. One of the Queeth, Chaugh, who keeps himself separate from the others, seems to be fairly intelligent and makes off-hand comments revealing future events.
The Queeth explain, with many interruptions from Chaugh, that every planet on which their species has lived has been destroyed by their enemies. They aim to protect their current planet, Queth, though Chaugh comments that the planet will soon be destroyed. The Doctor wants to help, though by this time the Gravis has lost his enthusiasm for the job. Chaugh begins counting down the minutes until the planet's destruction, seventeen, and his own death, thirteen.
The Queeth plan to place Queth in a sort of pocket dimension in order to protect it from its fate. They have a machine that will do the job, that has been powered by the minds of the intelligent Queeth. However, there isn't enough power to run the machine, and the Doctor deduces that one of the intelligent Queeth didn't take part — Chaugh. Chaugh comments on his imminent death, though the Doctor and Tegan try to stop him and fail. He jumps into the machine and dies, powering it up.
The Doctor figures out what has happened. There are no mysterious enemies — the Queeth are trapped in a temporal loop that has the planet removing itself from the universe, over and over again.
The Doctor takes the Gravis to Kolkokron, then goes back in time to take the surviving Queeth to Queth, to become their own ancestors.
- The Doctor tries to take the Gravis to Kolkokron.
- This story takes place immediately after the television story Frontios.
- This story was reprinted in Short Trips: Re:Collections.
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