13 user 8 critic

Elementary, Dear Data 

An attempt to provide Data with a challenging Sherlock Holmes holodeck RPG scenario backfires when its Prof. Moriarty character accidentally becomes self-aware.


Rob Bowman


Gene Roddenberry (created by), Brian Alan Lane




Episode complete credited cast:
Patrick Stewart ... Capt. Jean-Luc Picard
Jonathan Frakes ... Cmdr. William Riker
LeVar Burton ... Lt. Geordi La Forge
Michael Dorn ... Lt. Worf
Marina Sirtis ... Counselor Deanna Troi
Brent Spiner ... Lt. Cmdr. Data / Sherlock Holmes
Wil Wheaton ... Wesley Crusher (credit only)
Diana Muldaur ... Doctor Pulaski
Daniel Davis ... Professor James Moriarty
Alan Shearman ... Inspector Lestrade
Biff Manard Biff Manard ... Ruffian
Diz White Diz White ... Prostitute
Anne Ramsay ... Ensign Clancy (as Anne Elizabeth Ramsay)
Richard Merson Richard Merson ... Pie Man


When the Enterprise arrives a few days early at its rendezvous point to meet the USS Victory, the crew have a bit of leisure time on their hands. For Data and Geordi Laforge, it means a trip to the holodeck and 221B Baker St. With Data in the role of Holmes and Laforge as Dr. Watson, they take on a challenge from Dr. Pulaski that Data couldn't solve a genuine mystery. Data has a bit of time adjusting to a real mystery - as opposed to one for which he knows the outcome. In giving the holodeck computer its instructions however, Geordi's specifications for an opponent results in a far superior creation than expected putting them and the entire ship in danger. Written by garykmcd

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TV-PG | See all certifications »

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Release Date:

3 December 1988 (USA) See more »

Also Known As:

Elementary, Dear Data See more »

Company Credits

Production Co:

Paramount Television See more »
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Technical Specs


Sound Mix:




Aspect Ratio:

1.33 : 1
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Did You Know?


Moriarty's use of the phrase "that dark fellow" in reference to Geordi/Watson is the only reference to a human's race or skin color ever made on TNG. See more »


Nobody at the Bridge crew's hostage-situation meeting ever suggests the possibility of using the transporter to get Doctor Pulaski out of the Holodeck. Since a rogue AI program was commandeering the ship, this might not have worked, but it should have at least been considered. See more »


Moriarty: My mind is crowded with images, thoughts I do not understand, yet cannot purge; they plague me. You and your associate look and act so oddly. Yet though I have never met nor seen the like of either of you, I am familiar with you both; it's very confusing. I have felt new realities at the edge of my consciousness readying to break through. Surely, Holmes, if that's who you truly are, you of all people can appreciate what I mean.
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Featured in Star Trek: First Contact Review (2009) See more »


Star Trek: The Next Generation End Credits
Composed by Jerry Goldsmith and Alexander Courage
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User Reviews

Sherlock Data
24 February 2020 | by SeekingCinemaSee all my reviews

La Forge is frustrated with Data's ability to solve holodeck mysteries too quickly when playing Sherlock Holmes, ruining the element of suspense in the story. On a suggestion, he accidentally creates a villain who is capable of really challenging Data (in the form of Moriarty, Holmes' greatest adversary), which puts the Enterprise into a lot of trouble. Detective stories tend to make for great episodes, so why not throw in the greatest fictional detective of all time into a story? The plot is simply fantastic and the twist feels so obvious that you feel like you should have picked it up much before then. This episode again demonstrates how using sci-fi to alter the parameters of our universe can be used to tell a great story.

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