THE LEGEND OF THE DOCTOR

The episode would show the TARDIS Team returning to a planet they had already visited, Sebix, but twenty years after their original adventure there: at the time, one of the two races inhabiting the planet, the Sebixians, was using the second one, which they called the Nameless, as slaves; naturally the Doctor, Graham Ryan and Yasmin helped them guide a revolution and topple their oppressors - but after returning and being welcomed as heroes and living legends, they find out to their horror that the Nameless have now taken the name of Sebixians and reduced their old oppressors to Nameless, and have taken their vengeance by turning them into slaves and treating them even more cruelly than they were originally treated. The TARDIS Team now has to find a way to help the new Nameless without perpetuating a vicious circle.

Most of the story would be centered on the present adventure, but there would also be around ten minutes of flashbacks showcasing scenes from the original one (which, from the travellers' perspective, happened between Arachnids in the UK and The Tsuranga Conundrum); in the end, the Doctor would admit that the wounds are just too fresh, on both sides, to expect the two races of Sebixians to coexist peacefully: as such, the two peoples would start living on separate zones of the planet, and the Doctor would build enormous force fields around those zones; every year, a vote will be held, and only when a sizable majority on both sides will choose either peace or war the walls will go down. Before leaving, the Doctor would say to the leaders of both factions "Your choice", and I'm unsure between ending the story there or inserting a fifty-years-later epilogue where we'd see that, yup, they chose peace in the end.