Hannah Montana: The Movie

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Miley Stewart is struggling with her alter-ego and her popularity as Hannah Montana and keeping her double-life a secret from the media, but Oswald Granger (Peter Gunn), a sneaky undercover journalist for celeb magazine BonChic, becomes suspicious and vows to uncover her secret for his boss Lucinda (Jane Parr). Later, Miley (as Hannah) ends up in a fight with Tyra Banks over a pair of shoes that she wanted to buy for Lilly as a birthday present. When Oswald secretly follows her limo to the party, Miley is forced to attend as Hannah instead of herself, resulting in the guests turning their attention to her instead of Lilly, especially when Hannah is accompanied by Steve Rushton and Days Difference in her performance of "Let's Get Crazy".[10][11] Oliver Oken and Rico Suave try to stop Lilly from leaving, but the party is ruined by Rico's exploding "Happy Birthday Lilly" cake. Upset at Miley, Lilly accidentally tells Oswald that Hannah is from a place called Crowley Corners, Tennessee, not realizing that he is a journalist.
Robby Ray Stewart is furious over the fight between Hannah Montana and Tyra Banks reported over the newspapers and her general behavior in the past. He tells her that Hannah is going out of control and Miley needs to gain perspective and remember who she truly is. Instead of leaving for the World Music Awards in New York on a private jet, the Stewarts land in Crowley Corners, Tennessee, their hometown, for Miley's grandmother's birthday. Miley is angry at her father for the switch but Robby Ray points out that this is the life she could've been leading if she was not famous. Despite Miley's protests, Robby Ray decides to spend two weeks in Crowley Corners and ends up falling in love with a woman named Lorelai. Miley eventually warms up to her hometown when she rekindles a connection with her childhood friend Travis Brody after he helps her with riding her horse, Blue Jeans.
Nevertheless, Miley is eager to resume her Hannah duties and becomes chastened after Ruby snaps that she seems to want to be Hannah Montana more than she wants to be with her family. Oswald, acting on Lilly's tip, follows Miley to her hometown. Miley takes the opportunity to try to write new songs but when she is ignored by Travis, she develops writers' block. Meanwhile, there is a firm battle developing with the residents of Crowley Corners and Mr. Bradley (Barry Bostwick), a land developer who is planning to build a shopping mall on the site. Miley thinks it's a good idea at first, but is told that some of the town is being destroyed by the development. At a barn party that night, several singers contribute to the charity to save Crowley Corners, singing "Back to Tennessee" and "Crazier" by Taylor Swift. Miley sings as herself with "Hoedown Throwdown" until Mr. Bradley arrives. When he tells the towns people that they will not stop him, Travis suggests that Miley ask Hannah Montana, whom she claims to know after saving the singer's life in a surfing accident, to make an appearance to support the town, unaware that Hannah is Miley's alter ego.
Miley does not know what to do without exposing her secret or letting the town down until Lilly arrives, disguised as Hannah along with the band and crew, offering to help. As the two make up, Miley confides in Lilly that she has been having a rough time adjusting to farm life while trying to be herself and Hannah. Oswald sneaks up on the girls and takes pictures of them, believing Lilly to be Hannah Montana. That is when Lilly realizes she has inadvertently led Oswald to Crowley Corners and apologizes. The town is overjoyed to have Hannah Montana in town but Travis is unimpressed and admits to Hannah that he has had a crush on Miley for some time. As Hannah, Miley urges Travis to ask Miley out and he does. Miley accepts, but she has already been invited to dinner with the mayor by Lorelai.
Miley tries to be in two places at once but accidentally lets her guard down and is caught by Travis and a little girl mid switch. Miley finishes her song "Butterfly Fly Away", which she and Robby sing together to cheer up. Miley finishes the chicken coop that she and Travis were building. Travis is touched by the gesture and, he decides to go to the concert to support Miley.
Seeing Travis show up, Hannah suddenly stops mid song. She explains to the crowd that she cannot live a lie anymore, especially when she is home. Hannah then removes her blond wig, revealing her secret identity. She then sings her original song "The Climb" and announces that she's not going to be Hannah Montana anymore and that she'll be returning home to Tennessee for good. Afterwards, the crowd pleads with her to continue being Hannah Montana even promising not to reveal her secret, but Oswald is in the crowd and takes a picture. His twin daughters arrive, having missed the Hannah reveal, and their excitement and enthusiasm for Hannah convinces him to not sell the story, before calling Lucinda to tell her he quits. Miley kisses Travis and then returns to the stage to finish with the song "You'll Always Find Your Way Back Home". Miley leaves Tennessee to lead her double life again but with greater perspective and a better attitude.

Question: How does Oswald know to follow Miley to her hometown?
Answer: Lilly's tip