Star Trek: The Next Generation S02 E03 Elementary, Dear Data

"New stars. New stories. New worlds to explore."

Stardate: 42286.3. Data and Geordi become involved with a holodeck program about Sherlock Holmes and his investigations, when they create Sherlock's arch nemesis, Moriarty; however, modifications to the Moriarty character include the capability of out-smarting Data, which leads to some unexpected consequences.