A group of scientists have a deep-sea research facility called Aquatica. In the facility, they have discovered that there is an enzyme in shark brains that can re-activate human brain cells. They have three sharks: two "small" Gen I Mako's and a massive Gen II Mako, about 25 feet long. They have had to increase the shark's brain mass to get the enzyme, but the sharks are smarter as a side-effect.
Suddenly, during a storm, the sharks cause an accident which sparks off a chain of events which starts to sink Aquatica. The small group of humans then need to find a way out before they are killed.