Starring Colin Baker as the sixth Doctor, with Miranda Raison as Mrs. Clark. In the Galactic Census, idyllic Strellin is protected: landings by off-worlders are strictly prohibited. Unless, of course, those off-worlders are officials of the Galactic Census itself, come to investigate the origin of a mysterious sub-space signal, a signal no native of Strellin should be able to send. Breaking all local by-laws, the Doctor and Constance have only just landed on Strellin, too. But they and the Census officials aren't the only off-worlders to have come here. Inside a nearby monastery, the monks of the reclusive Brotherhood of the Black Petal are guarding a strange and terrible secret. Something might bring disaster not just to Strellin, but to every civilized world in the galaxy!