Until you hear him utter the phrase so irrevocably connected to Peter Brady — you know which phrase we're talking about — you may not recognize Christopher Knight in the premiere of Investigation Discovery's newest true crime series, Heartbreakers.

From the Sipowicz duds (short-sleeved button-down and tie) and the oversized glasses to the Creole accent and a combover that would make The Donald proud, Knight has left his Brady Bunch past behind to play Hurley Fontenot, a 1980s Texas junior high principal who may or may not have taken drastic action when the school clerk he left his wife for dumped him for the new football coach.

[Photos: TV Cast Reunions]

"It was the most fun I've had, probably ever, performing a character, because I don't get asked to do characters," Knight tells Yahoo TV. "In light of that, it was great fun, and it released me from my normal confines. When they offered me the role, I said, 'Well, obviously, you're offering me a role that doesn't seem to be me.' And in the character breakdown, I believe, [Hurley] was an East Texas Creole. When I heard that they were going to intertwine some of the actual footage of the man in with the re-enactments, I thought it would be impossible for me to try to be me in the role and have that footage have any bearing. It would be too jolting.

"So they were happy with my willingness to do the combover and all that other stuff," he says with a laugh. "Although, I've got to tell you, it's a little hard to watch. Frightening."

Knight's co-stars in "Shot Through the Heart," the premiere episode of Heartbreakers, with Growing Pains alum Tracey Gold. She plays Laura Nugent, the school clerk who carries on an affair with the married Hurley… until coach Billy Mac Fleming, played by The Bold and the Beautiful and General Hospital star Antonio Sabato Jr., comes to town.

Gold never worked with Knight before this project, but says she bonded with him over their child-star pasts and the fact that in one of her first roles — in the classic 1977 miniseries Roots — she co-starred with Brady Bunch dad Robert Reed. The 45-year-old actress tells Yahoo TV that she also signed on for Heartbreakers for the chance to play a character completely opposite her signature role. She was particularly excited that the '80s fashions she got to wear as Laura Nugent put her a lot closer to TV mom Maggie Seaver than Carol Seaver, the angsty teen she played on Pains.

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"I play a lot of moms. It was fun to play something where it's a femme fatale, caught in this love triangle," Gold says. "This kind of story from the '80s also appealed to me… you have to wear amazing clothes. One of the weird things was that as I got to put on these '80s clothes, it was really a lot like how [Joanna Kerns] dressed on Growing Pains — the shoulder pads, the wrap dresses, big button earrings and pearls. I was always wearing the kid clothes, the teenager clothes. So I was like, 'Oh, this is what I would be like in the '80s as a grownup.'"

Heartbreakers, which will air three episodes this summer with the possibility of additional installments if viewers find the series as addictive as ID's other true crime series, was sparked, producer Pam Deutsch says, from an internal discussion about what the network's signature crime re-enactments would be like if the actors were well-known Hollywood stars instead of unknowns.

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"Then it sort of evolved into what it is, which is a little bit like a movie of the week, sort of reminiscent of the Aaron Spelling nighttime soaps of the '90s," says Deutsch. "And when we started thinking about casting, we started looking at who were the people that really stood out during the '80s and '90s, all these people we grew up with, and I think there is something really powerful in the nostalgia factor. And in a lot of cases, we cast against type, as you probably noticed, which is also a lot of fun."

Brat Packer Judd Nelson, Baywatch alum Nicole Eggert, and Hercules himself, Kevin Sorbo, star in "Tainted Love," the Aug. 27 episode of the series, while Aug. 20's "Losing My Religion" is a deliciously over-the-top retelling of another love triangle gone very wrong, starring a trio of Melrose Place alums: Jack Wagner, Rob Estes, and Jamie Luner.

The episode is stolen by Wagner in a fun performance as Pastor David "Brother" Love, a charmer who uses his good looks and smooth words to lure the wife of one of his closest friends and congregation members into his bed. It all ends badly, of course, and if his fans are surprised to see the Daytime Emmy nominee in the series, that's the point, Wagner says. He, like the other Heartbreakers cast members, welcomed the opportunity to have a little fun with the kinds of roles they aren't frequently offered.

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"When they said, 'We're going to use real actors,' the main thing was this guy, this character," says actor and "All I Need" singer Wagner, who's about to begin touring to support his new CD release, "On the Porch." "When I read it, I said, 'God, I really know these people.' I'm from Missouri, sort of the mini Bible Belt area there. There are these people who really think they're God, some of the preachers, etc. I said, 'Listen, I want to give this guy a Southern accent. I really want to make this narcissistic, self-consumed guy believable. I really want to do something with him.' They went for it, and that's really why I did the show, to do something different, really dig into it."

Watch a sneak peek of "Losing My Religion":

Back to the aforementioned Brady Bunch nod in Knight's Heartbreakers premiere: There are actually two. One, we'll let you spot yourself, but the other, in which the actor, as Hurley Fontenot, repeats Peter Brady's famous "pork chops and applesauce" line, is just one of the little surprises that the Heartbreakers writers added to each script.

"We wanted to give the diehard fans little Easter eggs that we sort of lay throughout each episode," says Deutsch, who has also produced such ID delights as Tabloid, The Perfect Murder, and Who the (Bleep) Did I Marry? "Some of them are a bit more subtle than others, but we couldn't resist the 'pork chops and applesauce' line. Chris is such a great sport."

Adds Knight, who hasn't really left the Bunch behind, he and Brady sibs Barry Williams, Susan Olsen, and Mike Lookinland will be mixin' and minglin' with the series' most devoted fans at Brady Con this weekend in New Jersey: "I thought [the Easter eggs] were thrown in just for giggles at the table read. I didn't know they would be in the episode. But my thought was, 'OK, I'm probably going to do this guy with some kind of an accent, and part of 'pork chops and apple sauce' is not necessarily the words so much as the way it's said, with that Humphrey Bogart thing. I couldn't do it that way, the way that would have been direct, but then I thought, it doesn't really need to. It just needs to be said, and it will work for the purposes that they wrote it in there. I thought it was kind of cute."

Heartbreakers premieres Aug. 13 at 10 p.m. on Investigation Discovery.