The Stones of Blood is the third serial of the 16th season of the British science fiction television series Doctor Who, which was first broadcast in four weekly parts on BBC1 from 28 October to 18 November 1978. Part 4 was broadcast during the week of the show's fifteenth anniversary. The serial is set in and around an English stone circle and on a prison spaceship in hyperspace. In the serial, the criminal Cessair of Diplos (Susan Engel) is hiding on Earth after escaping the ship before being prosecuted for stealing the Great Seal of Diplos, the third segment of the powerful Key to Time. Plot Tracking the third segment of the Key to Time, the Fourth Doctor, Romana, and K9 arrive in modern-day Cornwall. They meet Professor Emilia Rumford and her friend Vivien Fay, studying the "Nine Travellers"--standing stones in Boscombe Moor. Their work is disrupted by a Druidic sect that worships the Cailleach, the Druidic goddess of war and magic, led by de Vries. De Vries and the sect are hostile to the newcomers, but the Doctor later finds the sect killed by mobile stones similar to those of the Nine Travellers and determines the stones must be alien beings that feed on blood. He and Emilia find evidence that suggests Vivien is older than she looks. Meanwhile, Romana catches Vivien awakening more stones with blood, and Vivien uses a device to send her to a spacecraft in hyperspace. When the Doctor and Emilia arrive, Vivien tells them that Romana will be safe before disappearing herself. The Doctor recognises the stones as Ogri, a life form from the planet Ogros. The Doctor constructs a projector to cross into hyperspace, leaving Emilia and K9 to guard it. On the spacecraft, the Doctor determines it is a prison ship, and inadvertently releases two floating globes called Megara that serve as justice machines. They accuse the Doctor of breaking a seal on the ship and prepare to put him on trial. Elsewhere, Vivien finds the Doctor's presence, and returns to Earth, awakening one of the Ogri and damages the Doctor's projector, but sparing Emilia's life as a friend. She and the Ogri return to the craft to attend the Doctor's trial. K9 guides Emilia in repairing the projector, allowing them to bring back Romana, along with an Ogri. They are pursued by the Ogri, leading them back to Vivien's cottage. There,