Laurie with the alien "rocks".
One of the parasites possesses Dr. Temple.
The Control Voice: Rocks. Silent, inanimate objects torn from the Earth's ancient crust. Yielding up to man over the long centuries all that is known of the planet on which we live; withholding from man forever their veiled secrets of the nature of matter and cosmic catastrophe, the secrets of other worlds in the vastness of the universe, of other forms of life, of strange organisms beyond the imagination of man....
Alien invaders pose as rocks in a geologist's lab and discuss their plans for invasion. However, Paul Cameron (Robert Culp) is able to hear them thanks to a metal plate engraved into his skull.
The Control Voice: Two black crystalline rocks. Unclassifiable. Objects on the border between the living and the nonliving. A reminder of the thin line that separates the animate from the inanimate. Something to ponder on. Something to stay the hand when it reaches out innocently for the whitened pebble, the veined stone, the dead, unmoving rocks of our planet.
Corpus Tropeling:
- Alien Invasion: These particular aliens are invading one human at a time.
- Aliens Speaking English: In this case it's aliens thinking telepathically in English.
- Big Creepy-Crawlies: The aliens transform into half-spider/half-crab parasites when they attack humans.
- Bittersweet Ending: As so often happens in The Outer Limits, the world is saved at a terrible price.
- Death of Personality: The aliens' victims suffer this; as the parasites take over their minds and bodies, the people they once were are destroyed.
- Driven to Suicide: The aliens try to do this to Paul, but it doesn't work.
- The Film of the Book: The episode is based on a novel by Louis Charbonneau, but takes major liberties with the original story.
- Happily Married: Paul and Laurie, until the parasites enter their lives (and Laurie's body).
- Properly Paranoid: One of the major themes of the episode. Neither Paul nor the people around him are sure of his sanity, but the aliens really are out to get him.
- Puppeteer Parasite: The aliens, although the people they possess are so severely transformed that they become Parasite Zombies who are unable to pass as normal.
- Screaming Woman: Laurie when the parasite attacks her — and who can blame her?
- Telepathic Spacemen: Played with. The aliens communicate with each other telepathically, but their mental contact with Paul is unintentional.
