Other than a brief sing-along to a tune on a car radio, her character doesn't do any crooning, something Cyrus deliberately avoided with her first lead in a live-action film that doesn't feature musical alter-ego Hannah Montana.
"I didn't want to sing in the film. We sang in the car that once, but that doesn't really count. I didn't want to do a performance thing," said Cyrus, who also contributes two songs to the soundtrack but figures she wants to keep singing and acting separate from now on.
"I never say I'm not going to do anything. Then if I end up doing it, I'm going to get a lot of crap. 'She said she'd never ...', you know? And I don't have time for that drama and people freaking out. But most likely, I'd like to stay away from music in films and do a little something less obvious."
Music in general is going on hold for Cyrus, who said an upcoming album will be her last for at least a few years, because she wants to concentrate on big-screen roles.
Cyrus, 17, has a handful of episodes left to shoot in the final season of "Hannah Montana," the Disney Channel series that made her a star. She has remained in the Disney stable for a "Hannah Montana" concert movie and feature film and led the voice cast with John Travolta in the studio's animated hit "Bolt."
"The Last Song," also from Disney, is a calculated effort by teen idol Cyrus to graduate into more grown-up territory and bring her fans along without alienating them as she moves beyond Hannah's happy world.
Cyrus' mother, Tish Cyrus, was the executive producer on "The Last Song."
"She and Tish, her mom and also her manager, are very astute people and knew precisely what would be the right next movie for Miley," said Julie Anne Robinson, who directed "The Last Song." "She's demonstrated that she has got emotional range and depth in this movie that can take her forward. I really think she could do almost anything."
Cyrus' character, Ronnie, is dealing with grim issues involving her divorced parents (Greg Kinnear and Kelly Preston) as she reluctantly spends a summer with her estranged dad, a composer and pianist who would love nothing more than to see his daughter resume her own abandoned piano studies.
Yet "The Last Song" also lets Ronnie put in some fun time at the beach with a hunky new beau (Liam Hemsworth, Cyrus' real-life boyfriend).
"It's a good stepping stone. Nothing too crazy. It's mature, but it's kind of for everyone," Cyrus said. "I think my next step, I'll get more and more mature and edgier, but I think it was the best steppingstone for me."
"The Last Song" was written specifically for Cyrus by novelist Nicholas Sparks, whose best-selling love stories include Hollywood adaptations such as "The Notebook," "A Walk to Remember," "Nights in Rodanthe" and this year's "Dear John."
Cyrus had expressed interest in taking on an inspirational story like "A Walk to Remember," and Sparks developed the plot and characters, then worked up the screenplay with his friend Jeff Van Wie. Once the script was done, Sparks sat down to write the novel version of "The Last Song," which came out last year.
Sparks tailored plot points to Cyrus, letting her choose her character's name (Ronnie was her grandfather's name) and developing sequences in which Ronnie tries to save a nest of endangered sea turtles after Cyrus mentioned she loved animals.
"The Last Song" turns melancholy, and Ronnie is forced to deal with betrayal and tragedy even as she reconnects with her father.
"This was not an easy role for Miley. This was not an easy role for any actress," Sparks said. "This was as hard as what Rachel McAdams did in 'The Notebook' or what Diane Lane did in 'Nights in Rodanthe.' Those were mature women who did those roles. She's 17 years old. It was not easy for her, and I thought she did a phenomenal job."
Cyrus said she has had an odd personal journey with the role that made her famous, Hannah, the pop-music superstar living a double life as an ordinary schoolgirl.
"It's kind of a weird cycle. I didn't really relate to her because I didn't know the famous life. Then I understood it, and I related to her. And now, I don't really relate to her anymore, because I've gotten more mature than that, and the show can only go so far for the channel it's on."
With the show nearing its end, Cyrus said she doubts she would resurrect Hannah for another big-screen movie.
"I think once the wig's off, it's off," Cyrus said. "I get begging fans. I think it's sweet that they're always supportive of the show, but my wish is they'll support me whatever I do, and that's what a true fan is. Whatever I'm doing, if the art that I'm making is making me happy, then respect my craft and respect the art that I'm making."
By David Germain