The hour begins with a very strange suicide, as a woman named Samantha shoots herself in the face before tumbling off a bridge. By the time Sherlock arrives on the scene the next day, the case is being treated as a murder -- the victim had called the police naming a music producer named Lucas as her assailant, apparently believing that he had kidnapped and tortured her sister. Holmes deduces her methods instantly.
Dissension in the Ranks
Back at the station, Lucas requests a polygraph test to acquit himself. While Sherlock is proven right, he instantly regrets it: after asking Lucas about his history with Samantha's sister Ally, Sherlock discovers that Lucas was subverting the polygraph with antiperspirant and in all likelihood did kill Ally.
Sherlock instantly clashes with Coventry, the detective who handled Ally's case, believing his police work to be sloppy. Coventry is frustratingly stubborn, and is so seemingly convinced of Lucas's innocence that he gives the potential killer Sherlock's address -- Lucas shows up that night, intimidatingly asking to "clear the air." While the captain is willing to investigate Sherlock's leads, Coventry reflects a growing dissatisfaction amongst the cops Sherlock routinely humiliates and belittles.
Sherlock seemingly catches a break when an old acquaintance of Lucas's comes forward, but when they call to follow up with her, Lucas picks up the phone. They race to make sure she's safe, but when they arrive they discover that the woman in question is a complete stranger -- the lead was from an impostor.
Sherlock realizes that Lucas is a "Catfish," creating online personas to keep tabs on his victims' loved ones. When Sherlock goes to confront him about it, Lucas quietly gloats over his superiority, baiting Sherlock into punching him in the face. This enables him to take a restraining order out on Sherlock and Watson, resulting in their removal from the case.
Though Sherlock nearly sabotages himself by staging an elaborate framing revenge, his breakthrough comes when he remembers Lucas's earlier alibi: he correctly said he was at work, and sure enough, his studio has a secret compartment. His success puts him back in the good graces of the NYPD, and the Captain publicly announces that anyone who doesn't like the way things are done here can take a hike.
I'm totally on board with the way this episode handles Sherlock's acerbic nature: while a lesser show might have him making Watson's desired concessions toward pleasantry at the end, he simply dominates at what he does and makes no apologies. That ensures that we don't betray the character by disingenuously curing him of his social problems on a regular basis, and makes for a far more interesting protagonist.
(Image courtesy of CBS)