On NBC's new medical drama The Night Shift, San Antonio Memorial Hospital's top docs don't clock out once the late-night hours kick in. As it turns out, they're just getting started!

"There's a lot of drama—a lot of high-octane intensity," Eoin Macken (best known from BBC's Merlin) says in a preview of the series, which follows his character, ex-Army doctor TC Callahan, as he battles flashbacks from his time serving in Afghanistan while treating patients stateside. "It's kind of like M.A.S.H.-meets-E.R."

Along for the ride at San Antonio Memorial are TC's best friend and former Army buddy, Topher (Ken Leung), and Drew (Brendan Fehr).

The Good Wife's Jill Flint also appears as TC's ex-girlfriend Dr. Jordan Alexander, but it's not the past relationship baggage that bugs TC most: It's his boss, Michael Ragosa (Freddy Rodriguez).

"[Our show] is like the whole idea that when a full Moon comes out, weird stuff happens. Like, that's when all the crazies come out," admits Macken, whose character isn't afraid to get into a physical altercation or two with Ragosa when it comes to acting in his patients' best interests. "There's a lot of drama, but the show still has this sense of hope."

For more of what to expect on The Night Shift, watch the preview clip above before the series premieres Tuesday, May 27 at 10 p.m. (EST) on NBC.