I've become a little tired of "Elementary" after watching two and a half seasons inside a couple weeks, but credit where it's due: the writing on this season is probably the best they've managed. Our new character is Shinwell (Nelsan Ellis), a patient Joan Watson (Lucy Liu) saved from multiple bullet wounds back when she was a surgeon. He's recently got out of jail, and is trying to rebuild his life. Shinwell is a charming guy: you know his history is troubled, but he turns out darker than you thought. Watson offers him help, and over the course of the season he becomes quite entangled with her and Sherlock (Jonny Lee Miller). What's unusual about this is that - unlike previous seasons - the appearances and disappearances of Shinwell didn't feel stapled on, they were part of the main plot. Shinwell becomes an informant on his old gang, the South Bronx Killas, determined to take them down. And over the course of the season we learn a great deal about that gang and about their biggest rival gang.
There are plenty of other single-episode mysteries to be solved. But the whole season winds up to the single most brutally brilliant plan the show has put on film as the leader of the South Bronx Killas almost manages an immunity deal and walks away. What makes this so impressive is its relative simplicity: to achieve it, all he had to do was slaughter an innocent to start a gang war, and betray everyone he knew.
It's a toss-up for me if this or the first season is the best. And to be saying that about the fifth season of any TV show is astonishing.