Doctor Who S12E09 - The Sontaran Experiment, Part One
Summary:
The Doctor, Sarah and Harry teleports to Earth to ensure the planet is safe for the survivors on-board Nerva Beacon to return to Earth and re-inhabit their world. Only to find a Sontaran named Styre has captured a group of humans and conducting experiments on them to discover the human body's weaknesses, as part of the Sontaran's goal for domination of the galaxy.
