The U.S. Navy's special group "Blue Water" hires a mad scientist to create the ultimate weapon for combat: a half-shark, half-octopus creature known as the "S-11." The Sharktopus is controlled by a built-in computer chip that allows it to follow orders from a remote control.
Despite initial success in testing, the Sharktopus breaks free during a live demonstration and goes on a rampage. It heads for the beaches of Puerto Vallarta, where it begins to terrorize tourists and locals alike.
A team of researchers led by Nathan Sands (played by Eric Roberts) and his daughter, Nicole (played by Sara Malakul Lane), set out to stop the Sharktopus before it can cause any more damage. They eventually join forces with a local adventurer, Andy Flynn (played by Kerem Bursin), who has a personal stake in stopping the creature.
The group struggles to find a way to defeat the Sharktopus, but it proves to be a formidable opponent. It has incredible strength, speed, and agility, as well as the ability to camouflage itself and regenerate limbs.
As the body count rises, the team races against time to find a way to destroy the Sharktopus before it can cause any more destruction. They eventually come up with a plan that involves exploiting the creature's weaknesses, but as they put their plan into action, they realize that they may have underestimated the Sharktopus's intelligence.
In the end, the team manages to defeat the Sharktopus, but not without a heavy toll. Many lives are lost, and the group is left to contemplate the dangers of playing God with science.