HBO: Tell us a bit about your character, Jake, on 'In Treatment.'

Josh Charles: Jake is in couples counseling with his wife Amy, and when we first meet them they've seen Paul, the therapist, a few times. They've been working hard for her to get pregnant the last couple years, having fertility treatments. Finally she does get pregnant, and she's not entirely sure if she wants to go ahead and have the baby. Jake is a frustrated musician. His parents are both professors, and his brother is a novelist. I guess he sort of rebelled against this intellectual concept and tries to express it through his music. I don't think he's fully reached the level of success that maybe he would have hoped for ... He also does some mill work and some custom cabinetry work on the side to make a living. I know people like that, people that play guitar and are good at singing and also kind of good with building things. So here's a guy who kinda likes to get his hands dirty.

HBO: The show was adapted from an Israeli version–how much did you draw from the earlier approach?

Josh Charles: I thought it was great, but we didn't watch a lot of it. I watched the first five and got really hooked into it, but I never saw anything more. I don't think Rodrigo [Garcia, executive producer] or anyone else really wanted to share too much with us about what happens to our characters. The only thing I really wanted to know was, "Does it make smart choices? Does it go places that are unexpected?" And he just gave me a little hint–and I don't want to give anything away–like, "Let me just tell you that in the next episode, this happens." And I was like, "OK. I'm on board."

HBO: The season has more than 40 episodes–was it tough keeping up with that schedule?

Josh Charles: I can't speak for anyone else, but for our part we shot two days for each session, and they weren't done back to back to back. So there were a couple times where we'd come out and shoot two, and then I'd have a few weeks off. The last three, I shot three weeks in a row. So that was sort of a great way to end it because it really did feel like a therapeutic process. It was intense, and I think it was certainly very intense for Gabriel, who had to be there for every one. I have a lot of respect for the patience that it would take.

HBO: The entire series is basically shot in one room–did you start to feel claustrophobic?

Josh Charles: What was really nice about the way that they shot it–the way Rodrigo kind of set the template and all the other directors followed–I never felt like the camera was anywhere near me. And yet, when you see it, it did capture a lot of stuff. I think that really helped because it just made you feel like you could just focus on your character and your other actors and what your intentions are in the scene. The camera was almost like an afterthought. Also, because we weren't really moving locations, that gave us the freedom to be able to have longer takes, which was hard but also gets you in a rhythm. You could really feel the flow of a scene, the way plays sometimes play out.

HBO: The set of Paul's office has so many knick-knacks–like all that nautical stuff–did you take anything home as a souvenir?

Josh Charles: You know what I took? When we shot the pilot, I went with one of the costume designers to find some of the right shirts for Jake, and we found this good flannel shirt at some vintage place in L.A. near the studio. I kept that shirt, which he wore twice in the show. I took the shoes, too, his sort of beat up Red Wings.

HBO: Months of therapy sounds a little dark–did anything funny or unexpected happen to lighten things up?

Josh Charles: I'm a giggler, so there were a few times–especially toward the end when we were doing a lot of episodes in a row with long and emotionally draining hours–there were some times when I started giggling and Gabriel started giggling and Embeth started giggling ... You feel like the naughty kid in the back of the class. And everyone is staring at you like, "OK..." Like, they're not in on the joke. That usually happens on every job somewhere along the way. I had it, with Peter Krause when we did 'Sports Night.' We just couldn't stop laughing. I embrace that; I think it's really funny.

HBO: Where will everyone be seeing you next?

Josh Charles: I just finished a play called "The Receptionist" last month. It was a sort of dark, twisted comedy. It had a real political bent to it that I was really proud to be a part of, and I thought it definitely got some people talking one way or the other. I also have this film I have a small role in called 'Brief Interviews With Hideous Men.' John Krasinski [from 'The Office'] directed it based on the David Foster Wallace book. A bunch of really good actors are doing cameos in it. I just had a blast working on it for a few days with John. It's about a lot of things guys do to women that aren't very cool, and I'm a sort of guy that continually breaks up with women in the same way. So ... I'll leave it at that.