Briggs and Charlie slip back into former aliases for a meet with a mid level heroin dealer who has connections to a major trafficker known as Odin Rossi, but when Whistler makes a surprise appearance the agents worry that their cover may be compromised. The only way to be sure will be for Charlie to pay a visit to her former CI, but using Whistler leaves her with a guilty conscience.
At the same time, Mike is finally rewarded with some answers about the Briggs investigation. It seems that some in the bureau suspect Briggs has been skimming from heroin busts for years. Could the entire Bello case be Briggs's play for the mother of all scores?
Elsewhere, Mike lets his attraction to Abby blossom despite Paige and Johnny's warning, and cultivates his relationship with Bello in order to position himself as the gangster's new bodyguard. But the closer Mike gets to Bello, the deeper he sinks into Bello's dangerous world.
Meanwhile, Briggs and Charlie's old covers stir up old passions, but when their potential meet with Odin is blown, Charlie is forced to go against her better judgment and turn to Whistler for help. But when her worst fears for Whistler are realized, she may end up crossing line that puts her career and her life in danger...