Long ago, in Devon in 1855, a mysterious event occurred. Overnight, during a terrible blizzard, thousands of hoofprints appeared in the snow. The tracks led on for miles... and no-one ever identified who or what caused them.

Many years later, the Doctor, Sarah and the Brigadier have come to Devon themselves, to visit a controversial scientific establishment in the wake of a mysterious death and rumours of strange occurrences in the vicinity.

But things are just about to get much, much stranger. Because they’re about to uncover the origins of the Devil’s Hoofprints... but is this one mystery that should have remained unsolved?