The Doctor versus The Master: A long-standing rivalry escalates on Sarn as the Master seeks to harness the planet's numismaton gas to regenerate and dominate, while the Doctor works to stop him and protect Peri and the Sarns.

The Doctor is dragged toward the flames as the Master smugly declares the Doctor's ultimate sacrifice to Logar, robbing him of future encounters. Before Timanov can complete the ritual, Turlough, …

As the Doctor and Peri depart toward the Fire Cave, Turlough remains hidden in the shadows, his silence masking the turmoil of his unresolved feelings for Malkon. The Master’s manipulations …

Peri witnesses the Master celebrating control over the numismaton gas, his rare energy source. While he boasts of harnessing its power for regeneration, she recognizes the blue flame as a …