England, the late 1970s. At Fetch Priory, Dr Fendelman's experiments with the new Time Scanner are disrupted by the mysterious death of a hiker, nearby. Then there's the mysterious skull, also being used as part of his work. A skull that seems to predate the evolution of mankind. What is the true role of the Fendahl in humanity's evolution?

The mystery surrounding the strange skull deepens. Thea is slowly succumbing to its influence while the Doctor prepares to battle a creature from mythology.

While Max prepares to tap supernatural forces beyond imagining, the Doctor and Leela investigate the legend of the Fendahl.

The Fendahl is returning to life, ready to consume everything in its path. Can the Doctor find a way to kill death itself?