A mysterious nun haunts the residents of the local nursing home. It soon turns out that an entire sisterhood serves under an old famous mythical beast...
- Ancient Astronauts: The Gorgons of Greek myth.
- Light Is Not Good: Oh, so very much.
- Continuity Nod: Clyde jokes that he'll never grow old because someday, he'll be able to transplant his brain into a robot. Sarah Jane responds with an exasperated sigh, likely thinking about the Cybermen.
- Mythology Gag: There's only one person a Doctor Who fan will be thinking of when Luke says "I need a screwdriver."
- Shout-Out: A nun threatens to show how her boss will "solve a problem like Maria."
- Stalker Shrine: Chrissie mistakes her petrified husband for one of these when she sees him standing in Sarah Jane's living room.
- Taken for Granite: With a story title like that, it's hard to think otherwise.
- The X of Y
- You Watch Too Much X: The nun's response when Clyde guesses she has tentacles under her habit. It turns out that the nuns are ordinary humans brainwashed into helping parasitic aliens.