Most of the actors on the show cite the "Route 285" and "River Dog" episodes as Roswell’s finest hours to date. And Heigl concurs, though she goes on to mention several other installments. "I would say that ‘Route 285’ and ‘River Dog’ are my favorites so far, but I liked ‘Heat Wave’ too. It spiced things up," she notes. " ‘285’ was really interesting. Shiri and I had some great moments, which I really liked getting to do. You saw everybody’s vulnerability in that one. Jonathan Frakes directed ‘River Dog’ and he did such a great job with it. ‘Monsters’ had a totally different feeling than the ones before it. We were introduced to this weird power Isabel has, which is going into people’s dreams. That has been my most interesting power so far. That episode also showcased this potential relationship between Maria and Isabel, and we’ll see where they go with that.

"I also like ‘The Balance.’ It’s very SF. We think Michael is dying, and I love what happens to everybody in this situation, how everybody reacts. I freak out, and it’s the one time Isabel really loses it. Up until then, even in the most extreme situations, Isabel had kept her head about her. In this instance, there was one scene in particular where I really just lost it. I loved that. [Co-executive producer-director] David Nutter and I talked about the scene. He initially thought that the character should remain strong, cool, calm and collected. I said, ‘But she has been through so much. FBI agents are chasing them. So many people know their secret. Max was just in a car accident [the week before]. I think it makes sense for Isabel to lose it for a minute.’ It’s just one scene. It’s not like she’s on the floor, catatonic or anything. We’ve also done an episode called ‘Toy House,’ which is really cool. It’s about me, Max and our mother [Mary Ellen Trainor], and our secret almost coming out. It’s really touching, and that’s why I love the show. We go into deep stuff as well as the really fun, supernatural SF stuff."

And where’s that episode in which other aliens – be they of the trio’s species or not of their world – arrive in Roswell? Heigl laughs. "Soon," she says coyly. "Soon. It’s coming. I haven’t read a script yet, but every script I’ve been reading seems to be leading up to it. So, we’re getting there."

Raised in Connecticut, she has been working professionally since she was nine years old, first as a child model, then as an actress. TV commercials paved the way to features, and Heigl counts among her credits That Night, My Father the Hero, Under Siege 2, Prince Valiant, Bride of Chucky and Bug Buster. Of the latter two vehicles, Heigl considers Chucky "a cool movie" and reports that she "doesn’t remember much" about the low-budget Bug Buster. Acting, she says, is the be-all and end-all for her. "There’s something about the camera, something about playing somebody else, figuring out who a character is, that I love," she enthuses. "I love discovering new people and becoming them. I’ve always loved doing that, and acting is second nature to me now because I’ve been doing it since I was little. It’s like a foreign language. When you learn it young, you just know it. It becomes a part of you. Acting is just a part of me.

"Sometimes I’ll sit on a set and complain because I’m bored and it’s taking forever to get to a scene. I’ll think to myself, ‘Why am I doing this if it’s so boring all the time?’ Then, I’ll get in front of the camera to do a scene and I’ll have two minutes of dialogue. And for those two minutes, I’m someplace else, I’m someone else, and I totally forget about everything. That makes up for all the hours of working, all the tedium, and I think, ‘This is why I love acting. This is why I’m here.’"

And, no doubt, Heigl could be around the Roswell set for years to come. That would mean lots of sitting around, plenty of tedium and, on the plus side, hundreds, perhaps even thousands, of opportunities to flesh out Isabel. Heigl weighed those pros and cons very carefully prior to agreeing to a potentially long commitment to Roswell. "Before you even go into a room to audition, you have to sign a seven-year contract. It’s a big deal," Katherine Heigl concludes. "I remember sitting there and thinking, ‘This is what I’ve avoided all of these years, because I was so afraid of getting stuck on a show and playing a character I would eventually get so bored with.’ But I just went ahead and auditioned for Roswell. Now I’ve got this character I continually get to develop and go different places with. Hopefully, that will continue. I want the character to grow and develop, and that’s always interesting. You can’t get bored with that.