Doctor Who: The Trial of a Time Lord: The Mysterious Planet (TV)

The Doctor is on trial for his life by the Time Lords for his interference in time and space. His grim prosecutor, the Valeyard, shows the court an adventure of the Doctor and Peri when they were visiting planet Ravalox. It was supposed to have been destroyed by a solar flare, but instead they find it perfectly habitable, home to a barbaric warlike tribe... and a second race underground, governed by a tyrannic robot. Something is very wrong in Ravalox, someone is meddling with time and space, and this time it's not the Doctor...