Eye of the Gorgon (1) (S01E03)

Sarah Jane (Elisabeth Sladen) and her young companions set out to explore rumors of a spectral nun haunting the nearby retirement home. Their adventure takes a twist when an elderly resident hands Luke (Tommy Knight) a strange alien artifact, suggesting there's more to the tale than initially thought. As they dig further, the group uncovers that the nun is linked to a covert order dedicated to guarding a fearsome alien being capable of petrifying its victims with just a glance.