Tori Spelling and Jennie Garth Tori Spelling and Jennie Garth

It's been 14 years since Jennie Garth and Tori Spelling said goodbye to Beverly Hills, 90210. Although they briefly reunited for the long-running Fox drama's CW spin-off, the two agree it had to be the perfect project — for them, ABC Family's Mystery Girls — that would get them back together on-screen for good.

"We have a lot to live up to because of 90210," Spelling tells "That was a pedestal and it would take something really special for us to come back together and do it right and I think this is it."

Debuting on Wednesday (8:30/7:30c), Mystery Girls stars the duo as alums of a '90s detective show who are brought back together by a real-life mystery. Charlie (Garth) is a suburban housewife and mother, while Holly (Spelling) longs for her glory days in the '90s when she was on television. Both of their lives are disrupted when a witness to a crime and a Mystery Girls fanatic will only speak to Charlie and Holly, and the former friends must reunite and put their TV crime-solving skills to the test.

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Like her character, Garth admits she was hesitant to jump back into television alongside her former co-star. "I had all this trepidation at first," she says. "I had a huge decision with career, our friendship, [reuniting] could be weird, but then I read the script and I loved it."

Fortunately, both felt as if no time had passed when they began filming.  

"When we did 90210, we were so close and we kept in touch over the years, but I wondered what working together [again] would be like," Spelling says. "We're not the same girls we were 20 years ago, our lives have changed and evolved, but all of a sudden it was the first day and we didn't miss a beat. We picked right back up where we left off."

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While fans of the pair are used to them bringing the drama on-screen, viewers will quickly see how much physical comedy — especially on the part of Spelling — is a part of the series. "Holly comes up with all these crazy ideas and is free-spirited and Charlie is more level-headed, but Holly drags her into it, but for the good," Spelling says. Adds Garth: "She gets her to live a little bigger." And the two have no problem with how outlandish some of the cases and plotlines are. "We love the physical comedy, in every show we were like, 'When can we act stupid?'" Garth says. "The show has a real fun camp element to it," Spelling adds. "But at the base of it it's grounded in the friendship between the two girls."

Off-screen, Garth says their friendship is similar to what Mystery Girls viewers will see. "Our banter in real life is our guideline," she says. "We talk sometimes and it makes no sense to anyone else."

And it's that dynamic that they're most excited for people to watch unfold. Says Spelling, "Fans will get to see us in a different way, but also see so much of the things people loved about Kelly and Donna in our characters because they're a part of us as well and they translate into Holly and Charlie."

Mystery Girls premieres Wednesday at 8:30/7:30c on ABC Family.

Watch Garth and Spelling talk about the show:

Jennie Garth and Tori Spelling on reuniting for Mystery Girls

Get more scoop on the show in Watch This Tonight:

Watch This Tonight:: Mystery Girls