After performing her new song "Make Some Noise," Hannah gets the crowd to reluctantly chant so they can be excited for the start of a new school semester. On Monday morning, Robbie tries to get Miley to get out of bed to get ready for her first day of high school, but she doesn't want to get up. So he threatens to get the water bucket. However, Miley doesn't believe him until Jackson comes in soaking wet and assures her that he would indeed do it, so she quickly gets up and gets ready for school.
At school, Miley and Lilly are excited for finally being the first day of high school. Unfortunately for Lilly, though, she has a zit on her face, so Miley offers to put some makeup on it to cover it up. Miley reveals that she brought her teddy bear from home in her backpack. However, she soon gets a text message on her cell phone saying someone knows her secret, and assumes someone knows she's Hannah Montana. Afterwards, Miley gets another text message from the same person saying her secret will be revealed to everyone at lunch. Now, Miley is worried that her life at school may be ruined. Meanwhile, Jackson befriends a new guy named Thor at school.
Miley tries figuring out who found out her secret, and asks Oliver if he told anyone, but he didn't, so now they have less than two hours to keep searching for the person. In chemistry class, Jackson's new friend Thor becomes his new lab partner, much to his dismay. Meanwhile, in Miley and Lilly's class, their teacher introduces Rico as their new classmate and reveals to Miley that he's the one who sent the text messages to her.
After class, Rico mentions that he had a camera phone and took a picture. In order to keep Miley's secret, he wants her to be his girlfriend, so Miley reluctantly agrees. Afterwards, he introduces Miley as his girlfriend to some of his friends. Later, Lilly tells Miley that Oliver has found Rico's locker where he's keeping the picture of Miley's secret in.
Jackson goes home for lunch, since he couldn't stand being around Thor any longer and complains to Robbie about his accent. However, Robbie reminds Jackson that he was once the new guy at school who got ridiculed for his own accent a few years ago. He tries to get Jackson to cut Thor some slack, but he refuses. Meanwhile, Oliver breaks into Rico's locker to get his cell phone where the picture is stored, but there's a monkey inside guarding it.
After seeing Thor being made fun of due to being a victim of a prank, Jackson decided to stand up for him. Miley, meanwhile, tries to stall Rico for time while Oliver and Lilly try to get Rico's cell from his locker. In order to prove Miley really loves him, Rico suggests that she kiss him. But, as soon as Miley is about to kiss Rico, Oliver and Lilly rush in and tell her they got the picture. However, the cell phone they took from Rico's locker was just a decoy; Rico has the real cell phone with the picture. In the end, Miley stops trying to be his girlfriend and tells Rico to send the picture to everyone if he really wants to, but he can't go through with it and gives Miley the picture. He admits that he only wanted to do it because he thought having a girl like Miley kiss him would make him cool. This makes her feel sorry for him, so she agrees to kiss him on the cheek, but turns around at the last second, making Miley kiss him on the lips. Now, she is furious and chases after him.
While Miley chases Rico, Oliver and Lilly find out that the big secret was a picture of Miley kissing her stuffed teddy bear she had brought to school with her, not a picture of her as Hannah Montana like they originally thought. As Rico runs by his locker, he asks his monkey in his locker for help, and it throws a banana peel on the floor, causing Miley to trip. As the episode ends, we see Rico's monkey selling snow cones from his locker, and Oliver getting sprayed in the face with syrup by the monkey when he asks for more.