In a thrilling episode titled "Planet of Fire," the Doctor and his companions, Tegan and Nyssa, encounter a group of scientists on a remote planet called Sarn. As they explore the planet, they discover a mysterious energy source that appears to be draining the life force of the planet's inhabitants. The Doctor soon realizes that the energy source is connected to a powerful alien entity known as the Salamanders, who are determined to harness the planet's energy for their own purposes. With the fate of Sarn and its people hanging in the balance, the Doctor and his companions must race against time to stop the Salamanders and save the planet from destruction.
