Originally airing on 7 April 1988, "Plan 10 from Outer Space" begins with a famous writer, Truman Smith the Third (Michael Constantine), taking off his blindfold and trying to confront Rexel 14, an alien who tries to kill him.
The scene shifts to Austin and Michelle, as they drive to the mansion, intent on discovering what the life-or-death problem is. When they arrive at the house, deep in New Mexico, they meet with the only other two residents of Truman's mansion; his maid Helga (May Britt) and his fifth wife, Trish (Sondra Currie).
This episode provides examples of:
- Assassination Attempt:
- Truman, a Science Fiction author, is convinced that the alien who has been advising him on all of his books wants to murder him. Rexel 14, however, is an Imaginary Enemy that happens to be associated with an electromagnetic anomaly due to the iron under the mansion.
- One of the women in the house successfully murders Truman, leaving evidence that implicates Rexel 14 instead. Austin has to prove which of them actually did it.
- Bluffing the Murderer: Because he didn't have any evidence to determine if Trish or Helga committed the murder, Austin has to trick the murderer into confessing by using the victim's sunglasses, which he says created a photonegative when the victim was electrified. When the murderer sees herself on the wall, she immediately starts trying to justify herself, admitting her guilt in the process.
- Closed Circle: Truman's latest wife attempts to leave the mansion once it is clear that Rexel 14 is going to kill her husband. She leaves with the housekeeper, but they're forced to return because the roads have been flooded by the recent storm.
- Deaf Composer: When the author, Mr Smith, sits down to write a novel, he's forced to wear a blindfold as he types on his typewriter. He says that he has to write this way because Rexel doesn't want to be seen, and Rexel is telling him the stories.
- "Eureka!" Moment: Reading the letter from the lightning rod company helps Austin figure out what really happened to Truman. He tells Mickey to get the other two characters and he's going to show them who "Rexel 14" and the murderer really are.
- "Everybody Laughs" Ending: While nobody laughs at the joke, Austin does end the episode with a reference to a very famous Imaginary Friend; the titular character of Harvey, warning him to watch his head on the low ceiling.
- Imaginary Enemy: Truman called for Austin's help because an alien called Rexel is trying to kill him. Austin is not impressed and assumes he's being pranked, until lighting appears in the house on a clear night and appears to try killing Truman.
- Imaginary Friend: For years, Rexel 14 was an extraterrestrial who helped Truman write hundreds of Science Fiction Novels. However, they had a falling out and now Rexel is his Imaginary Enemy. Imaginary because nobody else has seen/heard/met Rexel, but real enough to try killing him.
- Lightning Can Do Anything: Austin reveals that the supposed alien that used to visit Truman was actually due to a combination of iron under the mansion, the lightning rods, and water creating a short-circuit. Austin even remarks that "ball lightning" is extremely unpredictable.
- Minimalist Cast: This one episode featured only the two main characters, the murder victim, the murderer, and a Red Herring.
- No Celebrities Were Harmed: Truman Smith is a disguised reference to Isaac Asimov, one of the founders for this 1988 tv series. Like Dr Asimov, he is recognized as "the world's most prolific Science Fiction author", having written "over four hundred books" (which Dr Asimov had just achieved in 1988, ending the year with #405, The Sport Of Crime).
- "Scooby-Doo" Hoax: Austin has been called to a mansion in the desert of New Mexico. The mansion's owner, Truman, claims that an alien is trying to kill him. Unfortunately, Truman dies before Austin can prove him wrong (because someone else killed him). Austin has to explain who killed Truman and what Rexel 14 really is.
- Shout-Out:
- The title is a reference to the infamous Plan 9 from Outer Space, a movie about an alien invasion.
- The episode featured an author who had an illusionary friend named Rexel 14. At the end of the episode, Austin reminds Harvey to watch his head as they leave. Harvey is the name of an invisible rabbit from Harvey, that many people were convinced showed that Mr Dowd was insane.
- Yellow Lightning, Blue Lightning: The alien that Truman calls Rexel 14 is supposedly capable of controlling electricity. This manifests as blue/red balls of static lightning within the house.
