Held hostage? ‘The Patient’ tests Steve Carell’s will

“You don’t play the research,” Carell explains. “Because then it’s very thin. You try to arrive on the first day as prepared as you can be. But once you’re there, either it’s inside of you to a certain extent or it’s not.”

Adds Gleeson: “All I could do was play the person in front of me. There are all different sorts of people who kill people and Sam was incredibly specific.”

In the series, Gleeson’s Sam Fortner is a serial killer. He has taken a therapist (Carell’s Alan Strauss) hostage and, through the course of their relationship, reveals details about his past. To make sure he doesn’t try to escape, Sam chains Alan to a bed.

For the film’s director, it was a challenge to make sure a one-room story was interesting cinematically.

“It had completely different looks depending on the time of day and night,” director Chris Long says of the set.

For Carell, it was an interesting “what if” scenario.

“We were really in it for the duration of the day,” he says. “When I got chained in, it was a real lock with a real key and I thought, ‘Boy, if there’s an earthquake or a fire, I hope somebody thinks twice about letting me out of here.’ All of it added to the vibe of the space.”

Both actors didn’t consider “The Patient”  a TV series or an extended movie.

“Separating it out in terms of the form wouldn’t have been helpful for me,” Gleeson says. “It was just talking to the person in front of me and trying to figure out what the connection was.”

“The Patient,” as a result, has episodes of varying lengths. “Certain days, you’re like, ‘This is going to be such a heavy day because we have to go to some really dark place,’” Gleeson says. “And you would end up having the best time and go home.”

While Gleeson was able to pace around the room, Carell couldn’t. That limited his options but it also came with other perks: Gleeson’s character is a foodie, so he brings his hostage elaborate meals.

That trait was designed to turn the serial killer into a “fuller” human being, co-creator Joe Weisberg says. “You don’t ever associate a serial killer with food, so it seemed like that would be good.”

Carell, for the most part, listened.

“I’d like to delude myself into thinking I would be a good therapist,” he says. “I do enjoy listening to people and that’s probably the most important aspect of it. But I don’t think therapy means someone is going to solve your problems. I see a therapist as someone who helps you connect the dots and asks you things that might lead you to find and draw your own conclusions.”

Early on, Weisberg says, he and co-creator Joel Fields were eager to explore the idea of a serial killer who wanted to get better, “rather than just being the crazed killer you normally think of. We had to do research to find out if that was a real thing or something ridiculous that we just had made up. We pretty quickly found out that it was realistic.”

Both actors say they had a great time making the series.

“One of the things I loved about working with Domhnall was that he’s very serious about the work, but he doesn’t take himself too seriously,” Carell says. “That, to me, is the ideal combination. When it’s time to achieve what you’re both setting out to achieve, you’re of one mind and you go for it.

“There were moments of ridiculous levity between the most horrific moments. But we sussed each other out in terms of that and I think we were very tuned in.”

Adds Gleeson: “It was a perfect work experience for me.”

“The Patient” premieres Aug. 30 on Hulu.