 Ellen Brody still lives in the island resort town of Amity, and her sons Sean and Michael don t work at Sea World anymore, and some time ago, Ellen s husband Martin Brody died of a heart attack that happened because he was afraid of sharks. Sean is now a deputy in Amity. One night, during the Christmas season, Sean is called to untangle a log from a buoy, and when Sean goes to the buoy, he s killed by a great white shark. After hearing about this, Michael, who is studying to be a marine biologist, visits Amity with his wife Carla and his 5-year-old daughter Thea. Wanting to get away from Amity and spend Christmas with Michael, Carla, and Thea, Ellen goes with them to their house in the Bahamas on an airplane whose pilot is Hoagie Newcombe, and Hoagie starts falling for Ellen. Michael s friend Jake, who is also studying to be a marine biologist, lives next door to Michael. Sometime later, while Michael and Jake are out at sea, their boat is attacked by the shark that killed Sean. Michael and Jake try to tag the shark so they can keep track of it. Sometime later, while Thea and some of her friends are on a banana boat, a yellow boat shaped like a banana, the shark attacks the banana boat and kills a woman, leaving Thea in shock, but it looks like Thea will be okay. Carla is mad at Michael for not telling her that the shark is in the waters of the Bahamas. Michael and Jake didn t mention the shark, because they didn t want to upset Ellen and mess up her visit. Ellen believes that the shark is after her family and that it was trying to kill Thea instead of the woman it killed, so Ellen takes Michael s boat out to sea on a single-minded mission to find the shark and kill it while Michael, Hoagie, and Jake try to find Ellen because they re afraid the shark will kill Ellen before Ellen can kill the shark.