As Mike continues to work his way up into Bello's organization, Briggs and Charlie work together on an undercover job that sparks some old feelings between the pair and ends disastrously with the death of Charlie's CI and her risky choice to not let it all be in vain.
We also get Mike continuing to date Abby, something which gives Tuturro and Paige no end of fun while offering their couch quarterback philosophy (while also making side bets on Briggs and Charlie hooking up again).
By the end of the episode Mike has successfully cultivated his relationship with Bello and used a mutual knowledge and appreciation for westerns and Charlie is left with the repurcussions of choosing to shoot up in front of the paranoid middle man or walk away from their only chance of meeting the mysterious new heroin supplier.
Overall a solid episode more memorable for its small moments (Charlie and Briggs teasing Tuturro the next morning over what he overhead / Paige and Tuturro having some fun at Mike's expense) the the slower developing stories which leave one dead and Mike in a precarious new position.
You can find my full recap and review (with pics and video) at RazorFine