A freak hurricane hits Los Angeles, causing man-eating sharks to be scooped up in tornadoes and flooding the city with shark-infested seawater. Surfer and bar-owner Fin sets out with his friends Baz and Nova to rescue his estranged wife April and teenage daughter Claudia.
When a strange virus quickly spreads through a safari park and turns all the zoo animals undead, those left in the park must stop the creatures before they escape and zombify the whole city.
In search of a new energy source, Russia accidentally reawakens the Kolossus - a giant robot doomsday device from the Cold War. At the same time, a new Mega Shark appears, threatening global security.