McNulty and Freamon are seemingly having second thoughts on their scheme. Guilty conscious maybe? Omar is seeking revenge for Butchie and himself. The Mayor is trying to tackle the "homeless murders" as quickly and efficiently as possible, of course this is all at the detriment of other ongoing cases. Bunk is striving to do detective work on said cases by the book (or as "by the book" as they usually do) but is halted at every turn. Templeton spends the night with the homeless in order to investigate the murders, and ends up writing a real honest news story about a homeless marine who fought in Iraq. Who knew this guy had more than just career ambition? And finally Marlo is essentially breaking up the co-op telling everyone that he's the reason Prop Joe is dead and that he has the drug connect, which doesn't set to well with Slim Charles. Marlo is putting himself out there and risking a lot. The question is, will it pay off for him?
Oh and Nick Sobotka, last seen at the end of season 2, makes a cameo.