S04E20: A Bullet for Crockett

Sonny and Rico work undercover with a big dealer, Ricque ""Loco"" Mendez. During the police intervention, Sonny shot Loco, and the girlfriend of Loco shot Sonny. Members of the vice squad reminisce while Crockett lies close to death from the gunshot wound. We see why the other policemen love Sonny. At the end, we understand why Sonny is a cop.