On executive producers Jack Bender and David E. Kelley’s chilling AT&T Audience Network adaptation of Stephen King’s Mr. Mercedes, Harry Treadaway plays the titular serial killer, Brady Hartsfield. Over the course of the first nine episodes, audiences have witnessed just how tormented and demented of a psychopath Hartsfield is as he’s killed innocent people and continuously terrorized Det. Bill Hodges (Brendan Gleeson), who retired after being unable to solve a massacre, when 16 people were killed by a Mercedes.
A fan of King's novel, which is the first of a crime noir trilogy following Det. Hodges, Treadaway tells ET ahead of the season one finale that the reality these fictional characters lived in was so relatable, but portraying Hartsfield proved to be a challenge. To internalize the character’s past tragedies and voyeuristic approach to killing, the actor cleared out his local bookstore of texts on psychopaths and serial killers, getting a few strange looks at the checkout counter.
“Lots of really jolly things,” Treadaway jokes with regard to digging deep into stories about deranged personalities, adding: “In reality, and sadly, there are so many cases of people like Brady committing crimes like Brady that you don’t have to look too far to see the real deal out in our world. For me, that helped factor into something other than [playing] a character in a Stephen King novel.”
In fact, the real world perhaps paralleled the series too closely at times. While King’s 2014 book was based on an Ohio incident from 2011, vehicle-ramming attacks in Berlin, Jerusalem and Nice, France, have become even more prevalent in the three years since the book was first released. In fact, two days after ET visited the Charleston, South Carolina, set, a man drove a car into pedestrians in London, killing four people.
MORE: On Set of the David E. Kelley Adaptation of Stephen King's 'Mr. Mercedes'
At the time of our visit, Bender, who also directed the series, said that “given the world we’re in right now, taking a look inside one of these monsters may not be such a bad thing.” While speaking with ET by phone, Treadaway echoes that sentiment. “We want the work we’re doing to have an impact on the world at large,” he says. “In a weird way, to work on something that has parallels in our world, there’s something in it to discuss and address.”
And all those real-life horrors are perhaps why a show like Mr. Mercedes, which was renewed for a second season, continuing Hodges’ story with Finders Keepers, and the many other King adaptations have resonated with audiences this year. “There’s something about the suburban horror with him, the residential nightmare that he paints so well,” Treadaway muses. “The idea that you’re living on the street with someone who could be plotting something like that is terrifying. Sadly, we’re in a world where we’ve become aware of that more and more.”
Though, it’s nothing like being in the mind of someone like that, which the actor was while filming Mr. Mercedes. Committed to the role, the actor found himself struggling to not take Hartsfield home with him each night. “Trying to not be dreaming it and think of it first thing when you wake up -- I have to say I wasn’t always successful being able to do that,” says Treadaway, who’s starting to pick up some awards season attention for his portrayal. “It was a character you really needed to get into to get under the skin of.”
The Mr. Mercedes season one finale airs Wednesday at 8 p.m. ET/PT on Audience Network.