"My masters will follow the example of Rome... our mighty empire bestraddling the whole of civilization!"

It is AD 79, and the TARDIS lands in Pompeii on the eve of the town's destruction. Mount Vesuvius is ready to erupt and bury its surroundings in molten lava, just as history dictates. Or is it?

The Doctor and Donna find that Pompeii is home to impossible things: circuits made of stone, soothsayers who read minds and fiery giants made of burning rock. From a lair deep in the volcano, these creatures plot the end of humanity - and the Doctor soon finds he has no way to win...