Ace returns to Perivale to visit her friends, only to find they have been abducted to an alien planet by a race called the Cheetah People who were shown the way to Earth by the Master. The Doctor must find a way off the planet before they all succumb to its savage influence.
The Doctor and Ace arrive at a secret military base during World War II, where an ancient evil from the Doctor's past prepares to make his final deadly move. As hideous vampires rise from the sea and Russian commandoes begin to close in, they are confronted not only with a mystery from the distant past but also a terrifying vision of mankind's future...
Knights from a parallel universe arrive on Earth to find the legendary sword Excalibur. Only the Doctor and Ace, with the assistance of Brigadier Lethbridge-Stewart, can save the Earth from total catastrophe.
