Just before their heat starts at the Turtle Bay Resort Invitational, Alana and Bethany run into their mutual friend Keoki, who is skateboarding with some friends on a nearby half-pipe. Keoki invites Alana and Bethany to go night surfing with some friends at the next full moon, which is a Thursday. Bethany playfully tells him they will show up if they have nothing better to do, then the girls walk away to get ready for the competition.
Both girls do exceeding well at the competition, with Bethany taking first place and Alana taking third. At the awards ceremony, Bethany invites both Alana and Malina onto the winner's podium, but a jealous Malina shoots Bethany a resentful look and stomps away. After the competition is over, Bethany and Alana's parents excitedly tell the girls that surfing apparel company Rip Curl wants to sponsor them, which makes them squeal with delight.
Alana and Bethany then go shopping at a beachfront swimwear shop at Rip Curl's expense. While inspecting the merchandise, Alana and Bethany make humorous and sarcastic comments about the swimsuits they show each other. While the girls are shopping, surfing rival Malina walks over to them and smack talks that every day she's in the water training for the Hawaiian Island Regionals, she'll be thinking of Bethany. Alana drolly replies, "Creepy!" and laughs when Malina saunters away.
Late Thursday night, Alana and Bethany sneak out of the house to meet some friends to do some surfing under the full moon. At midnight, a glorious fireworks display lights up the beach party Alana and Bethany are attending below. The next morning, Cheri serves the girls breakfast and lets them know she knows they snuck out to go surfing the night before. Bethany apologizes and promises to ask permission before going night surfing again. At around that time, Alana's father Holt and brother Byron arrive in a pick-up truck to take the girls to the beach.
During a lull in the surfing action, Alana and Bethany lie on their surfboards and chat about clothes. To everyone's extreme shock, a shark attacks Bethany by biting off the arm that she had nonchalantly been dangling in the water minutes before. Alana screams for her father, and Holt and the others surround her while they all paddle frantically towards the shore. Holt removes his rash guard and fashions a tourniquet with it for Bethany's severed arm. Understandably hysterical, Alana doubles over and starts to vomit on the sand, but Holt calls her back to help him and Byron transport Bethany to the truck on her surfboard. As they are speeding down the highway, Holt sees the ambulance and pulls over so the paramedics can transfer Bethany into the emergency vehicle. Alana, Holt, and Byron then follow the ambulance to the hospital in their truck. Due to her trauma over the attack, Alana is unable to accompany her father when he goes to visit Bethany after her surgery.
Despite the nightmares she's been suffering since the attack, Alana summons the courage to visit Bethany in the hospital. Bethany is glad to see her best friend and encourages her to do the photo shoot the girls had originally scheduled with the Rip Curl company. When it comes time for Alana to do the photo shoot, Bethany shows up to support her best friend. Alana tells her that she should be doing the photo shoot too, but Bethany is too shy about her injury to do it at that point.
When Bethany decides that she's ready to try surfing again, she naturally invites Alana along to be a part of the moment. Before entering the water, Alana asks Bethany if she's scared, to which she replies that she's more afraid of not surfing again. Alana cheers loudly with the rest of the Hamilton family when Bethany, after several false startts, manages to stand up on her surfboard on her own.
At the Hawaiian island regionals, Alana, disgusted with surfing rival Malina Birch's attempts to steal Bethany's waves, cuts Malina off and is disqualified from the competition for interference. When Bethany returns to the beach after the pounding surf has cracked her surfboard in two, she explodes at Alana for dropping in on Malina like that. Later the two go surfing and apologize to each other for their snappish behavior.
Alana makes a fantastic showing at the Rip Curl Nationals Championship when she competes with her friend Bethany and rival Malina. Although Malina takes first place, Alana ends up in second place. At the awards ceremony, Alana cheers on Bethany when Malina invites her up to the winner's podium and announces that she would like to share her win with Bethany.