HBO's prohibition-era drama Boardwalk Empire, which stars Steve Buscemi as bootlegging Atlantic City gangster Nucky Thompson, ended its uneven third season this past fall with a bloodbath of epic proportions, so it's no surprise they're already casting some new faces (even though all luckily of our heroes survived the fallout).

The Hurt Locker's Brian Geraghty is reported to have accepted a recurring role for the upcoming fourth season playing Loren Knox, and Prohibition agent with ulterior motives newly assigned to Atlantic City.  Ron Livingston (Band of Brothers) has also been cast in a series regular role as a wealthy out-of-town businessman who starts up a relationship with Gillian Darmody (Gretchen Mol).  For more on these casting choices (with minimal spoilers), hit the jump.

With Nelson Van Alden (Michael Shannon) seeming to have gone to the dark side last season by becoming a member of O'Banion's crew (although we didn't get a follow up with him in the finale) and poor (crooked) Prohibition agent Stan getting blown up last year, it's no surprise that the show has sought out a new agent to fill the void.  After all, someone has to be on the side of the law, right?  I'm not sure what these "ulterior motives" Geraghty's character Knox might possess, but let's hope he will never, ever be as irritating as last season's newcomer Bobby Cannavale as Gyp Rosetti (like that would even be possible).

On the romantic end of things, it looks like Gillian survived (sigh) that mega dose of heroin and will struggle to remain relevant to the series by carrying on another affair (let's hope she doesn't drug and drown this one).  It sounds like Livingston's character could help Gillian re-open her brothel business with real money, something that Lucky Luciano (Vincent Piazza) was never willing to really invest in during his relationship with her.

The series is slated to return in its usual fall slot, but in the meantime it's probably due a proper rewatch, at least of that fantastic final episode.