She’s chased by the paparazzi through a park. The media is frenzied over her did-she-or-didn’t-she engagement. Her blond lock framed face graces the covers of endless magazines. Her off-screen beau is another famous celebrity. Meet Sandra Dee … and, for that matter, Kate Bosworth.

In Beyond the Sea, opening Dec. 17, Bosworth stars as goody-two-shoes movie star Sandra Dee. The film, a longtime pet project of director Kevin Spacey (who also stars as Bobby Darin), examines the legendary entertainer’s life and his tumultuous affair with Dee.

At first, Dee – a former teen idol and legendary recluse – wanted nothing to do with Beyond the Sea, a biopic of her late husband Darin. But Bosworth, who plays Dee in the film, says that the "Gidget" actress attended a private screening of the film and enjoyed it quite a bit.

"She saw the movie last night and loved it. So that’s a good thing. She had a private screening. I don’t think she could quite handle an audience just yet," says Bosworth, who turned into Hollywood royalty after her turn as a strong-hearted surfer girl in 2002’s Blue Crush. "Someone told me today, ‘Sandy saw the movie – she loved it!’ Good news."

Bosworth, 21, has the same "gee-wow" innocence that infused Dee during her own career. It seems, then, that playing this character would be a simple feat for such a similar actress. But Bosworth denies the claim.

"It was a process. For me it was first internal; I had to figure her out. She had this image of being this picturesque golden girl, almost goody-two-shoes," says Bosworth, "and it was Kevin Spacey, when I first met him, who said, ‘She has so much more beyond the image.’ And that intrigued me."

Bosworth read the book written by Dee and Darin’s son, Dodd, imagining that the interviews would be honest because Dee would be most candid with her son, "and she was," says Bosworth. "She went through the whole marriage, her upbringing, the sexual abuse as a child. Basically everything. That’s when I really got into her."

Into her head, at least. Other than her nauseating virginal image, canonized in the song from Grease "Look at Me, I’m Sandra Dee," the actress’s look was often thought to be iconic. While Bosworth laments entering Dee’s psychology, entering her wardrobe gave her no complaints whatsoever.

"It was fun! I just love everything that’s classic," says Bosworth. "I felt like her style was pretty classic. Her hairdos were sometimes a little bit outrageous, but those were the times. The clothes were really beautiful.

"The only thing that was really annoying were the tights. She sometimes wore these really thick tights, almost dancer tights, and those were really annoying. But it was so freezing in Berlin where we shot the movie, so I was thankful," she adds.

This preparation, however, wasn’t enough, and days before shooting began the actress had an anxiety attack. "I said, ‘I’m going to have to have five coaches on this movie! Movement coach, speech coach, everything! I’m going to need to copy Sandy completely and I don’t know if I can do this,’" says Bosworth.

"I went to Kevin and said, ‘We’re going to need to figure out how to make me exactly like Sandra Dee.’ But he told me I had to take it with a grain of salt and that no one knows exactly what she was like and [instead] to [just] create her. So that’s what I did."

And how did she do?

"I don’t even know how I did, you know," Bosworth says of Dee’s non-response. "I think I’ll hear from her. It just has to be so bizarre to see yourself onscreen. I completely understand her apprehensiveness to see the film. It must be hard for her.

"I don’t know how I’d feel if someone wanted to create me up on screen. It would be so weird! To sit back and watch someone re-create scenes of my life," says Bosworth. "Bizarre."

Beyond the Sea releases in theaters Dec. 17.