Mark O’Brien (Halt and Catch Fire) has been cast as a series regular opposite Aldis Hodge and Kevin Bacon in Showtime’s drama pilot City on a Hill, executive produced by Ben Affleck and Matt Damon. Michael Cuesta (Homeland, American Assassin) is directing and executive producing.

Written by Chuck MacLean (Boston Strangler) based on an original idea by Affleck and MacLean, City on a Hill is set in Boston in the early ’90s when the city was rife with violent criminals emboldened by local law enforcement agencies, in which corruption and racism was the norm, until it all suddenly changed. The drama is a fictional account of what was called the “Boston Miracle.” The change agent is District Attorney Decourcy Ward (Hodge), who comes from Brooklyn and forms an unlikely alliance with Jackie Rhodes (Bacon), a corrupt yet venerated FBI veteran who is deeply invested in maintaining the status quo. Together they take on a family of armored car robbers from Charlestown in a case that grows to encompass and eventually upend Boston’s citywide criminal justice system.

O’Brien will play Jimmy Ryan, the younger brother of Frankie Ryan, who is the leader of the Two Saints Gang that robs banks in Boston. Jimmy has addiction problems, psychiatric problems and is generally unpredictable, unreliable and selfish. Against his better judgement, Frankie lets Jimmy join his gang on a bank job.

O’Brien just completed production on Jason Reitman’s The Front Runner with Hugh Jackman, as well The Darkest Minds. O’Brien’s recent credits include series regular on The Last Tycoon and recurring roles in Halt and Catch Fire and Hannibal, as well as the Oscar-nominated Arrival.

O’Brien is repped by Don Buchwald & Associates, Thruline Entertainment, The Characters Talent Agency and Lichter Grossman Nichols Adler & Feldman.