Season: Three — Episode: 3 Director: Jerry Levine — Writer: Robert Hewitt Wolfe — Aired: November 13, 2014 — Viewers (millions): 6.53 Summary: Sherlock helps a math genius from his network of "Irregulars" experts after he stumbles upon a body while participating in a math puzzle competition. Joan attempts to extend an olive branch after she learns about Kitty's past.
So just to recap, I've spent the last few months of my life playing a game that was designed to kill me.
One of Sherlock's "Irregulars", Harland Emple encounters a dead body when solving a math puzzle linked to a huge prize amount. Sherlock and Harlan find that at least 16 mathematicians are solving the puzzle. When two dead bodies are found in the course of solving the math puzzle, the police infer that perhaps the killer is targeting mathematicians. A clue is given to Sherlock and team when a few mathematicians direct them towards a website run by someone called Mo who is working as something of a math crusader to demonstrate and shame the unethical uses of math. The person also has an FBI bulletin against them for having put some secret data on the website in their quest to detail the flaws in the calculation.
Harlan decries Mo's involvement and says he is a genius. Sherlock deduces that Harlan is Mo. Harlan admits this and is shamefaced in admitting he was copying Sherlock's actions. The team finally locates the killer when a misguided clue sends the killer in search of Mo to the wrong address.