The Stones of Blood

The Doctor and Romana are about to embark in search of the third segment of the Key to Time when an aural warning tells them to "Beware the Black Guardian." They venture outside to find themselves near the Nine Travellers, a group of cromlech or standing stones in Boscombe Moor, Cornwall. Also interested in the location is aged archaeologist, Professor Amelia Rumford, who is surveying the stones along with her friend, Vivien Fay.