On Amity Island a young woman disappears after a late-night skinny dip. When her partial body washes up on shore the next morning, Police Chief Martin Brody is certain it’s a shark attack and orders the beaches closed. Concerned more about the town’s economy than public safety, the medical examiner and mayor pass it off as a ‘boating accident,’ and the beaches are reopened 24 hours later. The mayor insists they remain open for the busy and lucrative 4th of July weekend. When a young boy becomes the second victim, his grieving mother offers a reward to whoever catches and kills the shark.

Pandemonium erupts when everyone with a boat frantically hunts the shark for the reward. Chief Brody calls in oceanographer, Matt Hooper who examines the remains of the first victim and surmises she was killed by a large shark. Meanwhile, several bounty hunters catch a tiger shark.

Town officials are satisfied this is the killer, but Hooper is skeptical. He and Brody cut it open to look for human remains. Finding none, they realise the killer is still out there.