With some leisure time available, Data and La Forge embark on a holodeck adventure based on Arthur Conan Doyle's Sherlock Holmes stories - with a doubtful Dr Pulaski in tow. When the Enterprise computer is instructed to prepare a mystery that would be a genuine challenge for Data, it somehow bestows sentience on one of the game's characters - a character that now wants to be free from his holographic prison.
Katherine Pulaski is such an appalling racist. She's been on the Enterprise for three weeks now, and despite all evidence to the contrary she continues to treat Data like a mechanical thing rather than as a self-aware, conscious individual. It's all rather offensive, particularly since Pulaski seems to afford more respect to Professor James Moriarty, the holodeck character that has become self-aware. You'd expect there to be some payoff by the end of this episode, where Pulaski apologise to Data and promises to treat him with respect, but instead we're found wanting.