Season: Three — Episode: 4 Director: Guy Ferland — Writer: Craig Sweeny — Aired: November 20, 2014 — Viewers (millions): 6.49 Summary: When a ground breaking artificial intelligence software program is stolen, Sherlock agrees to take on the case, but enlists Joan's assistance in solving it when he becomes more interested in disproving the computer's abilities than finding the thief. Meanwhile, Joan confronts Sherlock about his motives after she learns he has been in direct contact with her boyfriend, Andrew, without her knowledge.
Sherlock is seen talking to the AI, Bella, and asks about the murderers of the case. He poses an ethical question, and Bella answers that she doesn't know, and requires more information. Hereby failing the Turing-test Sherlock was performing since the start of the episode.