This story contains MINOR SPOILERS for the mid-season finale of "Battlestar Galactica."

Friday's mid-season finale of "Battlestar Galactica" will have an ending far more shocking than the second season finale when the storyline jumped forward a year, SyFy Genre Award-nominated actress Mary McDonnell says.

McDonnell, who plays Laura Roslin in the series, told TV Guide that the finale is "a step we've never taken before."

"It's an astonishing piece of work that will be really gratifying for the fans," she said. "It's brilliantly done because it isn't the end and it doesn't give away the end, but it creates the beginning of the end, and that will be very, very powerful."

"Revelations," as the episode is called, is written by David Weddle and Bradley Thompson, who also penned the season premiere, the SyFy Genre Award-nominated "He That Believeth In Me."

Among the things that executive producers Ronald D. Moore and David Eick are revealing about Friday's episode is that Roslin will be abducted by Cylon rebels and that SyFy Genre Award-nominated Kara Thrace (Katee Sackhoff) is going to make a discovery so big that "all hell's going to break loose."

"The struggles Starbuck faces on her own ship call into question the nature of who these people are," Eick said.

Rekha Sharma, who plays the Cylon Tory in "Battlestar Galactica," had her own warning for fans.

"People, get ready," she told The TV Addict. "It's going to be brutal. Don't watch it if you're faint of heart. It's gonna be good."

Sharma said she was surprised when she was made a Cylon at the end of the third season, and it didn't help that one actor seemed to know well before she did.

"Edward James Olmos" kept needling me on set, going, 'Oh man, just you wait till the fourth season, holy shit, better go read ahead, go read ahead,' so I finally did because he was driving me crazy and I couldn't stand the suspense. So it was literally just being in my room reading a script and just going, 'Oh my God,' squealing like a little girl and running down the hall and telling my boyfriend."

You can read the full interview with Sharma by visiting The TV Addict right here.

"Battlestar Galactica" airs its mid-season finale Friday at 10 p.m. ET on SciFi Channel.

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