Lights, camera, action!
Dun dun.
A terrifying, unseen force beneath the water kills a girl as she's skinny dipping in the ocean off Amity Island. Chief Martin Brody investigates and concludes it was a shark attack. He tries to close the beaches, but the mayor of Amity, Larry Vaughn, pressures him to forget it. It's almost the Fourth of July weekend and he's afraid of ruining the tourist season by making the attack public. He convinces Brody to record the death as a boating accident. Soon after, Brody's at the beach with his family when a young boy is attacked and dragged underwater in front of dozens of witnesses, including the boy's mother. She advertises a reward of $3,000 for anyone who can kill the shark.
Dun dun.
A fisherman named Quint offers to kill the shark for $10,000, and Brody asks the oceanographic institute on the mainland to send one of their shark experts. Enter young, cocky Matt Hooper, a marine biologist who's been obsessed with sharks since age twelve, when he accidentally hooked a small shark while fishing and had to swim to shore while the shark ate his boat. He examines the remains of the shark's first victim and concludes it was no boating accident, but an attack by an unusually large shark.
Dun dun.
A group of bumbling Amity fishermen catch a big tiger shark, but Hooper is sure it's not the culprit. The dead boy's mother confronts Chief Brody, blaming her son's death on his failure to close the beach. Brody and Hooper cut open the tiger shark, discovering that it's not the one that ate the boy. That night they go out in Hooper's boat to search for the shark. They discover the corpse of a local fisherman, Ben Gardner, along with a great white shark tooth stuck in the wreck of his boat. Hooper pries out the tooth but drops it when he sees the pale, decapitated head of Gardner floating inside the submerged boat.
Dun dun.
Mayor Vaughn refuses to believe there's a great white shark prowling the ocean and insists they keep the beaches open, much to the Chief's frustration. The next day, despite all the precautions taken by Brody and Hooper, who are furiously pacing the beach and scanning the water, the shark returns and kills a boater right in front of Brody's son Michael. Brody convinces a traumatized Mayor Vaughn to hire Quint to kill the shark. Quint grudgingly agrees to let Hooper and Brody accompany him on the hunt. The running joke is that Brody, Chief of Police in a beach town, is scared of the water. He's not happy to have to do this but feels he owes it to the people he was hired to protect.
Dun dun.
The three men head out on the ocean to find the great white. Quint ridicules Hooper's fancy scientific gear as tensions run high between all three men. They search for the shark for some time before he suddenly appears, revealing his unbelievable size. A traumatized Brody, the first to see him, delivers his classic line, "You're gonna need a bigger boat." The men chase the shark and Quint shoots a harpoon into his back, attaching a buoyant barrel meant to tire the shark out. The barrel doesn't even slow him down, and he return to the depths. That's some shark.
Dun dun.
That night, the men get drunk and bond over their scars and sing sea shanties as they wait for the shark to reappear. We get some backstory on Quint's vendetta against sharks. He was one of the survivors of the USS Indianapolis, a ship that was sunk after delivering bomb components during WWII. Many of the crewmen went overboard and were killed by sharks as they waited for days to be rescued.
Dun dun.
The shark reappears and rams the boat. Quint shoots another barrel into his back, but he still manages to submerge. The next morning the shark returns and Brody tries to radio for help. Quint takes a baseball bat to the radio; his obsession with killing this shark has clouded his judgment, we'd say. They try to tow the shark home, but he's too strong and instead begins towing them back out to sea in an incredible display of power. When the men try to flee from the shark, he chases the boat until its damaged engine blows up. Very Moby-Dick.
Dun dun.
At this point, even Quint has run out of ideas. He asks Hooper what he can do with his fancy equipment. Hooper goes underwater in his shark cage with a poison-tipped spear, but the spear floats to the ocean floor after the shark sneaks up from behind and rams the cage. The shark totally destroys the cage and Hooper's barely able to swim out of the cage and hide in a cave on the sea floor.
Dun dun. Dun dun. Dun dun dun dun dun dun dun dun…
The enraged shark leaps onto the back deck of the boat and, in a horrible sequence, kills the screaming Quint. As the boat sinks, he comes back for Brody, who manages to lodge a compressed air tank in the corner of the shark's mouth. The shark circles around to attack again. At the very last second (of course) before the boat sinks, Brody grabs Quint's rifle and shoots the air tank, which explodes and obliterates the shark. Hooper resurfaces, and Brody and Hooper paddle home on some floating debris.