La Forge tells the computer to create a character capable of defeating Data. Thus the character of Dr. Moriarty suddenly gains sentience (sapience), and kidnaps Dr. Pulaski. Data figures out where she's been taken and encounters Moriarty, who has learned all about the Arch command to summon the holodeck controls, and has thus learned all about the Enterprise.
Eventually Picard himself enters the Holodeck and speaks to Moriarty, who wishes to leave the confines of the Holodeck. Picard explains this is impossible; however, he promises to work on it. He saves the program, and promptly forgets about it for the next few years (until Season 6's "Ship in a Bottle").
This episode provides examples of:
- Absentee Actor: No Wesley in this one.
- Bilingual Bonus: When he is informed that Moriarty can take control of the ship, Picard's reaction is "Merde" (French for "shit").
- Breaking the Fourth Wall: An in-universe example, as Moriarty becomes aware of the Enterprise beyond his holodeck simulation and even draws a picture of it.
- Call-Back: Data previously emulated Sherlock Holmes in the season one episode "Lonely Among Us", which is implied to be the reason Geordi set up the holodeck program for him.
- Eagle-Eye Detection: How Data seeks to emulate his literary hero. Unfortunately for Geordi's sense of immersion, what Data detects is the plot points from the original Holmes stories, allowing him to skip to the end.
- Exact Words: Geordi doesn't ask the holodeck to come up with a villain capable of defeating Sherlock Holmes—he asks it to create a villain capable of defeating Data. This is basically treated as the technological equivalent of a Literal Genie.
- Failsafe Failure: Geordi may be the Chief Engineer, but he is still only a lieutenant. Who the heck designed the Enterprise's computer operating system such that his administrator privileges are not only so absolute that he could accidentally lock himself out of the system, but every other officer above him in the chain of command, including Captain Picard?! It's even worse when you consider that those administrator privileges are transferred to Moriarty, who is essentially just a program written by the computer itself!
- Gone Horribly Right: The holodeck does exactly what Geordi asks it to do, just in a completely unexpected way.
- Holodeck Malfunction: As is usual whenever the holodeck decides to endanger the entire ship, they cannot just turn it off.
- Innocuously Important Episode: Continuing where "11001001" started, this episode explores the idea of self-aware holographic programs, which would pave the way for other such characters like the Doctor on Star Trek: Voyager and Vic Fontaine on Star Trek: Deep Space Nine.
- Mathematician's Answer: The computer's first attempt at creating an original Holmes story is simply to slam two of the canonical storiesnote together.
- Nice Hat: Several throughout the episode, starting with Data's obligatory deerstalker and culminating in Picard's very fine silk top hat.
- No Challenge Equals No Satisfaction: Geordi is disappointed by how easily Data solves their first mystery, so he tells the computer to create a new antagonist that could challenge Data.
- Oh, Crap!: Data and Geordi's steadily mounting panic as they realize Moriarty has seen through the Holodeck's illusions are nothing compared to their reaction when he gives them a drawing of the Enterprise.
- Plot Hole: If Moriarty, as a holographic construct, can't leave the holodeck, how does Data take Moriarty's drawing of the Enterprise out to show to Picard? The original shooting script addressed this, but the final scene was cut.
- Refrain from Assuming: This episode's title is almost universally misstated as "Elementary, My Dear Data".
- Sequence Breaking: This is essentially the reason for the plot. As Data's android memory has retained the plots of all the Sherlock Holmes stories as if by heart, he ends up "solving" the mystery before the story, "A Scandal in Bohemia", has progressed far enough to give him all the clues. So, the characters decide to reprogram the simulation in such a way as to create new plot elements and an adversary capable of matching Data—in this case, a sapient Moriarty.
- Sherlock Scan: Naturally, this occurs in the Holmes simulations.
- Title Drop: When she sums up why Data can't understand the joy of solving a mystery, Dr Pulaski says, "It's elementary, dear Data."
- Wham Line: From Moriarty.Moriarty: <to himself> That dark fellow there used the word "arch" and then, I wonder... arch!
- What Measure Is a Non-Human?: Moriarty insists on his right to exist, as he is fully self-aware and in all respects a sapient being save that he lacks a physical body.