Tannis orders his troops to make a ground assault, and they land near Stonehenge. They move towards London, but are confronted by UNIT troops, led by Lieutenant Colonel Speedwell. Abandoning his troops to their fate, Tannis seeks out the Doctor. He finds Ace first and starts to beat her to death, before the Doctor finds them. Tannis baits him, that he dare not use his powers to save Ace, as he had not saved Antimony. However, Tannis must be stopped. With no surviving Time Lords, Tannis would then be free to misuse his own powers. He had not done so before so that other Time Lords would not act in concert against him. With the choice between himself abusing his powers, or leaving Tannis free to abuse his, the Doctor must use them to stop Tannis and does so, even though it means his own passing. Declaring himself a God of the Fourth, the Doctor unleashes the power, and afterwards, he and Tannis are gone.