The Shieldstarted with a WHAM episode: the pilot ends with Detective Vic Mackey killing the newest member of the Strike Team in cold blood. From there, it got even crazier.
"Homewreckers", which features the death of the single-mother prostitute Connie Riesler.
"Barnstormers": Secondary Strike Team member Ronnie is disfigured by Armadillo Quintero and left in Vic's home.
"Streak And Tips": Shane and Tavon get into a massive fight, which culminates in Tavon having a car accident on the way home due to the injuries he sustained.
"Mum": Police Captain David Aceveda gets raped by Mexican drug dealers, kicking off a series-long plot.
"Kavanaugh", which features the "Holy Shit" moment of Lem being arrested by Jon Kavanaugh, after he realizes that his achilles heel (his ex-wife) has been exposed.
"Post Partum": Shane kills Lem due to a misunderstanding, in what of the most shocking scenes in the series.
"Parricide": Shane goes on the run after a failed attempt to have Ronnie and Vic killed blows up in his face. Vic rather than serving out what little time remains until his retirement turns in his badge so he can get to Shane before the police and prevent him from spilling the beans on all the Strike Team's crimes.
"Possible Kill Screen": Vic - believing Corrine has been arrested and having gotten immunity with ICE before Ronnie - tells all of his crimes to Olivia Murray to protect Corrine. Aside from Vic implicating Ronnie (his last remaining friend), Claudette arrives and witnesses him admitting to murders too late to do anything about it.
"Family Meeting": The Grand Finale as the Strike Team is destroyed once and for all. Shane kills himself and his family, Vic sells out Ronnie for immunity and Vic's family are in Witness Protection. Vic also takes down the drug cartel and gets his job at ICE. However, because of their utter disgust at his confessed crimes Vic's bosses place him in a desk job that's sure to make him miserable. Also, it's heavily implied that (1) the ICE agent he tricked into the immunity deal will look for any way to make him violate the terms and get him sent away, and (2) he's going to pull out all the stops to make damn sure that doesn't happen.