Piranha II: The Spawning (released internationally as Piranha II: Flying Killers) is a 1982 American independent horror film directed by James Cameron in his feature directorial debut. It is written by Charles H. Eglee (under the pseudonym H.A. Milton) and stars Tricia O'Neil and Lance Henriksen, who would later star in Cameron's The Terminator and Aliens. Part of the Piranha film series, it is the sequel to the film Piranha (1978) directed by Joe Dante.
Cameron, previously a special effects artist for Roger Corman, was hired as director after executive producer Ovidio G. Assonitis fired his predecessor. The production was fraught with difficulties arising from Assonitis' exerting an unusual amount of creative control, hiring an Italian crew that didn't speak English and preventing Cameron from viewing any footage during the editing process. The exact degree of creative control Cameron had has been disputed by multiple sources, with some claims arising that Assonitis fired Cameron after two weeks and directed the film on his own while others maintain that Cameron was present for the entirety of principal photography.
After the film's release, Cameron largely disowned the film for many years, but has since acknowledged it as his directorial debut.
A Caribbean coastal resort, Hotel Elysium, is menaced by a series of vicious marine animal attacks originating from a nearby sunken shipwreck. Diving instructor Anne Kimbrough's student is one of the victims, but her estranged police officer husband Steve refuses to let her see the corpse. The death is abnormal for the area and wildlife, which she knows as a former marine biologist. Soon after, two women and a man are killed by piranha which has developed the ability to fly.
Concerned, Anne finds that she is being frequently bothered by tourist Tyler Sherman, and decides to take him with her to the morgue to get a look at the body. A nurse comes in and kicks them out, unaware that a piranha was hiding in the body. It kills the nurse and escapes through a window.
In her hurry, Anne left her credit card behind at the scene. Anne and Tyler have a one-night stand. In the morning she begins to study the pictures of the corpse, and is horrified by what she discovers. Steve arrives, throwing the card at her, angry that she went to the morgue and that she has a man in her bed. She tries to warn him of what she has discovered, but he ignores her and thinks she is a murderess.
Anne then tries to cancel the diving sessions. Her manager first pretends to be concerned, but quickly fires her, thinking she is crazy. Attempting to capture one as proof of the incoming threat, she is intercepted by Tyler, who informs her that he is a biochemist and member of a team which has developed the ultimate weapon: a specimen of genetically modified piranha, capable of flying. He explains that his team lost a cylinder full of these fish in the water earlier.
Gabby provides the proof Anne needs to Steve, showing him that they are a serious danger, as they are now eating each other, having devoured everything else. At a meeting, Anne tries her best to reason with the manager, to no avail. Steve provides a piranha wing as evidence. Steve tells her that she cannot trust Tyler, because the army says he is crazy. She argued that Tyler has just been using her to get the message of the piranha out for him, to protect both himself and the residents of the hotel.
Later, a piranha attacks Gabby's son and kills him, leaving Gabby to vow revenge. Anne tries to dissuade him, but fails. Having ignored Anne's advice, the manager, Raoul, hosts a nighttime fish party to capture grunion. Unfortunately for the residents, the piranha join the hunt. Anne gets a man named Aaron to patrol the beach but he is lured to the sea where the piranha kill him. During the fishing party promoted by the resort, the piranhas fly out of the water and attack the guests. Anne leads the survivors into the hotel, where they shut the doors and windows. Gabby tries to attack the flying piranha, but they easily overwhelm and kill him.
In the morning, the piranha leave as they do not like the light. Tyler and Anne decide to undertake Gabby's plan, and blow up the ship to kill the predators. Meanwhile, Anne and Steve's son Chris has been hired, against their wishes, by a local ship 'Captain' Dumont and his daughter Allison. They sail away and strand themselves on an island. Getting lost at sea, they try to set sail again, heading straight toward the wreck.
When Chris and Allison are stranded in a raft above the shipwreck, Anne and Tyler arrive in a motorboat and dive down to the wreck to plant the timer charges that Gabby left behind. With only 10 minutes to get out of the wreck before the bomb explodes, Anne and Tyler are trapped in one of the sunken ships rooms by the murderous piranha who all return to the wreck. Steve, piloting a police helicopter, ditches the chopper and swims to Anne and Tyler's motorboat where Chris and Allison are. Steve powers up the boat and takes off. Down in the wreck, Tyler gets stuck and is eaten by the piranhas. Anne escapes out of a porthole, then grabs the anchor, allowing herself to be pulled away by the motorboat on the surface. The bomb detonates, destroying the sunken ship and all the piranha with it. With all the piranhas dead, Anne swims to the surface and is picked up by Steve, Chris and Allison in their boat.