Jacob H Knoll and Gillian Williams in ‘Belleville.’ (Teddy Wolff)

It didn’t take long for actors Gillian Williams and Jacob Knoll, who play spouses Abby and Zack in the Studio Theatre production “Belleville,” to develop chemistry and intimacy. It was forced upon them the first day of rehearsal, when they were asked to jump into a bathtub to take promotional photos.

“We walked in and they were like, ‘All right, you guys, hop in this bathtub together and hold each other, and we’re going to fill it up with water.’ ” It was, Knoll says, “kind of a brilliant way to start this process, because it’s intimate.”

“Belleville,” by Amy Herzog, is an intimate play. Not only does the entire show take place in the couple’s small Paris apartment, but it also is a portrait of a vulnerable marriage. Zack is a young doctor who has taken a prestigious job in Paris with Doctors Without Borders. But his codependent wife has stopped trying to learn the language or make friends, and is finding herself increasingly isolated. When Abby finds Zack at home watching Internet porn when he’s supposed to be at the office, the questions that are asked and answered begin to chisel away at their relationship.

“It begs the question, ‘Do we ever really know someone?’ You see . . . the slow ripping apart of hearts,” Knoll says.

It is a turbulent experience, Williams says, for both audience and actors.

“There are sometimes roles or plays where you go, ‘Man, do I want to live there?’ ” she adds. “It’s really a testament to what a well-written play it is, because we can throw it down for hours. There can be snot and tears, and when we’re done for the day, we’re done for the day. . . . You get the catharsis. So you don’t leave the theater at night still feeling like you’ve got crap trapped in your emotional gutters.”

The two actors’ rapport offstage helps prevent that feeling, too. As does their set: It’s a working apartment, complete with appliances and running water. The characters shower and walk around semi-clothed, just like someone would in his or her own home.

“It’s part of this world. I think it makes it human,” Knoll says. “It makes it feel more real.”

But realism isn’t as easy as it looks.

“These things you take for granted as a human being — you just do them. But somehow the second you’re onstage, you’re like, ‘Why can’t I open this door? Why am I so awkward when I try to sit down, or eat, something?’ ” Williams says. “There’s something that happens to actors when you just try to be a human being. It’s the hardest thing in the world.”

It’s even harder, Knoll says, than understanding Zack and Abby’s troubled marriage, which is quite simple when he lays it out.

“I feel like it’s about these two people trying to figure out how to love each other as best they can. If you keep that in mind, it’s really a love story where some f----- up s--- happens.”


Wednesday through Oct. 12 at Studio Theatre, 1501 14th St. NW.
202-332-3300. www.studiotheatre.org. $44-$88.