Beginning in 2009, McDermott starred in the TNT drama "Dark Blue", playing a veteran cop who heads a squad of undercover LAPD officers. The show ran for two seasons, each consisting of ten episodes. In 2011, McDermott starred on "American Horror Story" on FX as Ben Harmon, a psychologist and cheating husband. He returned to as a new character due to the series' anthology format, this time portraying Johnny Morgan. In 2012, he appeared in three films: "The Campaign", playing Tim Wattley, a campaign manager, "The Perks of Being a Wallflower", as the father of main character Charlie (Logan Lerman), and "Nobody Walks", as Leroy. He appeared in the action thriller "Olympus Has Fallen" as a treacherous Secret Service Agent who helps a group of terrorists seize control of the White House.