Reynolds plays Caine, a gunrunner who becomes stranded in a small port in the Red Sea. He meets a seductive woman who propositions him to dive into shark-infested waters off the coast for scientific research. However, when Caine realizes the woman and her partner are actually treasure hunters, the action starts to heat up both above and below the water.
Steven Miller wakes up one day to go fishing with one of his students at the college. However Steven has a flat tire and can't make it. His student goes out to fish along with his dog down by the river. As he is throwing his line out into the water, a shark knocks him down and eats the bottom half of the student. Steven sees the body by the beach and thinks the death might be from a Mountain Lion. When he goes home, his son asks him if he can go to the arcade for a while. While at the arcade, 3 of his friends come up to him to remind him about going tubing over the weekend. The son tells his father that they are all going hiking instead of going tubing because Steve hates the water. Then at the gate that stops things from the ocean coming into the river, the gate is jammed and the gate operator goes down and tries to fix it. The shark then grabs him with his teeth and eats him. His partner reports that the operator is missing to the police but they can do nothing. That night, a bum named Sarge spots a shark swimming through the river and he runs in the bar and everyone laughs at him. The next day, Steven goes to find the sheriff. He tells the Sheriff that there is a shark in the river. The sheriff does not believe him and drives off. Later, a couple goes jet skiing in the river. The shark then knocks the lady off the jet ski and eats her. As the husband looks for her, the shark knocks him off the jet ski and eats him too. That night Steven goes to Sarge and asks him about the shark he saw. Sarge tells him about the shark and how he was in the navy and what he did when he was younger, then the Sheriff comes up to him and asks him to come with him. The Sheriff brings him to the body of the male jet skier and the sheriff now believes that the shark is actually in the river. The next day, some friends go out on the river on their pontoon boat. The shark then hits the boat and the hits it again knocking one of the friends off. The shark sinks his teeth into him and blood comes out of the friends mouth. Steve then gets a call from his wife telling him that she found out that their son was going tubing in the river. Steven tells his wife to call the police and that he is going to find their son. The police gets her call and bring Sarge along with them. Steven then drives off and meets the sheriff on the bridge over the river. The sheriff gives him a harness and they dangle him from the river and Steven grabs his son. However, his friends are still in the river. So, they tie the rope to a tank of gas and dangle it over the water. The shark bites on the tank and Sarge gets the gun and shoots the tank. The shark blows up and Steven and his son walk to his wife and then head home.
While wind surfing near the seaside community of Port Harbor, a young man is killed by a giant Great White Shark. Author Peter Benton and professional shark hunter Ron Hammer realize the truth, but ambitious governor William Wells refuses to accept that a shark threatens their community. Fearing that a canceled wind-surfing regatta would derail his gubernatorial campaign, Wells has shark nets installed. But the sounds of teenagers splashing in the surf leads the shark to rip through the nets. The next day, the shark plows through the wind surfers, knocking them off their boards. But rather than eat the scattered teenagers, the shark targets the governor's aide and eats him.
Sonny Stein, who is played by Richard Jaeckel, learns while working as a marine salvager in the Philippine Islands, that he has a connection with Mako sharks, and is given a medallion by a Filipino shaman. Becoming alienated from society, Stein lives alone in a small stilt house offshore of Key West, Florida. He develops an ability to telepathically communicate with sharks. He then sets out to destroy anybody who harms sharks. People enter into his strange world to exploit his abilities and his shark "friends," including an unethical shark research scientist and a morbidly obese strip club owner (Buffy Dee) who wants to use a shark in his dancers' acts. Stein then uses these sharks to get revenge on anybody he considers a threat.
Kate is a shark expert whose business has been failing since a shark attack killed a fellow diver under her command. Once dubbed "the shark whisperer", Kate is haunted by the memory of the attack and unable to get back into the water. With bills piling up and the bank about to foreclose on Kate's boat, Kate's ex-boyfriend, Jeff, presents her with a lucrative opportunity: to lead a thrill-seeking millionaire businessman on a dangerous shark dive – outside the cage. Battling her self-doubts and fear, Kate accepts the proposal and sets a course for the world's deadliest feeding ground – Shark Alley.
Pisces, or Pi (Freddie Prinze, Jr.), is a 5 year old orange fish who lives happily with his parents Pike and Piara in the polluted harbor of Boston, Massachusetts, until a fishing boat scoops them from the sea. Pi's parents manage to help him escape, but cannot escape themselves. Before Pi's parents are taken away, Piara tells Pi to promise her he would go live with his aunt. Pi's porpoise friends Percy (Trent Ford) and Percy's mother Meg (Megahn Perry) take Pi to live with his aunt Pearl (Fran Drescher) and cousin Dylan (Andy Dick) on an exotic reef. When Pi reaches the reef he is 25 years old and has stayed with the porpoises for most of his life. As he tries to settle himself in this new world, the sweet and well-meaning Pi makes some good friends in his new home. When he first arrives, Pi immediately falls in love with Cordelia (Evan Rachel Wood), a celebrity fish who has appeared of the front cover of National Geographic Magazine.
Dans un petit port de Floride, des barracudas agressifs se mettent brusquement à attaquer des plongeurs. Cette catastrophe laisse les habitants et les touristes dans une incompréhension totale jusqu'au jour où un biologiste, Mike Carfield fait une troublante découverte. L'usine chimique Jack Chemical Co. qui se trouve à proximité des eaux serait-elle à l'origine de cette menace ?
Steven (Hugo Stiglitz), a US-born Mexican businessman, arrives in a Mexican fishing/resort village for a vacation on a yacht anchored off shore. One of the local fishermen, Colorado (Roberto Guzmán), takes Steven with him when he goes to haul in the sharks he has caught. Colorado is annoyed to learn that another shark has taken a huge bite out of one of his captured sharks. Steven says he feels bad for the sharks, then shrugs, "that's life." He then decides to scope to local beaches for sexy women. He sets his sights on Patricia (Fiona Lewis), an Englishwoman on vacation. They have a whirlwind romance but break up when Steven can't decide if he is in love with her. Steven is extremely jealous, however, when she begins a relationship with Miguel (Andrés García) a womanizing swimming instructor at the nearby resort hotel. While Steven stews on the yacht, Patricia and Miguel have sex. Then she goes skinny dipping in the ocean for a morning swim and is eaten by a large, apparently emphysemic, 19-foot-long (5.8 m) tiger shark.
A small oil rig located on a small river in Louisiana hits it big and former oiler John Sanders (who quit when a blowout occurred on a rig he was the boss of and four men died) and his friend Emery are hired to take his ex-wife Kelly and her boss to the location. Nearby, some thugs do diving for stolen goods that were dumped nearby. Unfortunately, at the same time, a huge bull shark enters the river and starts terrorizing and killing people. Emery's people, a local tribe, believe that the shark is a spirit that supposedly protects the area where the well is manifested in physical form as vengeance for the oil rig.
Fin et April passent leurs vacances d'été en Floride. Pas de chance ! Cet État, habituellement ensoleillé, est détrempé par la pluie. Mais il y a pire : un Sharknado s'annonce. C'est toute la côte Est, d'Orlando à Washington, qui cette fois-ci sert de garde-manger aux requins volants. Fin et April vont devoir, une fois de plus, sortir le grand jeu.
Fin Shepard and his ex-wife April Wexler are flying to New York City to promote How to Survive a Sharknado and Other Unnatural Disasters, a book April has written about the Los Angeles sharknado. As the plane comes in for a landing through a storm, it is battered by airborne sharks, losing an engine. Sharks enter the plane, killing passengers and crew, including both pilots. While Fin successfully lands the plane, April's hand is bitten off by a shark while she attempts to shoot it with an air marshal's handgun.
Seven Tulane University undergraduates – Sara, Nick, Beth, Malik, Maya, Blake and Gordon – drive to Sara's family vacation home on a private lake. There, Sara encounters her old boyfriend, Dennis, and his friend Red.
Invité à Londres par le gouvernement britannique pour participer à une conférence de l'OTAN comme spécialiste en combat contre les requins, Fin est entraîné par Nova à explorer un temple souterrain situé sous Stonehenge. Des peintures rupestres leur apprennent que l'humanité a déjà été confrontée aux Sharknado à la préhistoire, mais les humains ont conçu un artefact (en forme d'aileron dorsal de requin) pour contrôler ces tornades. En s'en emparant, Fin et Nova déclenchent involontairement un Sharkado mondial qui frappe successivement les plus grandes villes du monde : Londres, Rio de Janeiro, Rome, Tokyo... Leur fils Gil ayant été aspiré par la tornade à Londres, Fin et sa femme April la poursuivent à travers le monde, pour tenter de sauver leur fils et empêcher la fin du monde.
L'histoire se déroule cinq ans après les événements de Sharknado 3. La tempête porteuse de requins tueurs est de retour et la cible des squales est à présent Las Vegas. Après avoir ravagé la ville, le Sharknado se déplace et frappe plusieurs états du centre des États-Unis, sans façade maritime, qui n'ont pas l'habitude des cyclones se formant au-dessus de la mer, mais plutôt des tornades continentales. En se déplaçant et frappant diverses installations (barrage Hoover, champ de pétrole, transformateur électrique, centrale nucléaire), la tornade change de nature en se chargeant de matières de plus en plus dangereuses : poussières, pierres, pétrole, feu, électricité à haute tension, et même radioactivité. Toute la famille Shepard, enfin réunie, va devoir unir ses forces pour en venir à bout.