Incredible sightings and events, all revolving around the sea, begin to pour in from all over the world. It would appear that there is a strange , powerful new type of sea creature appearing all over the globe. Oceanographers all over are studying this new creature. These oceanographers and researchers include Laura Daughtery, David Lee, a Pentagon official and Dr. Aleksander Cirko, a government scientist. Richard Connelly, an insurance salesman, is also interested in the creatures, and his interest leads him to Laura.

Meanwhile, a young boy, Miles, discovers an odd egg near the ocean, and, excited, decides to care from it and wait for it to hatch.

The oceanologists, Rich and Laura, see the dead body of a new, groundbreaking sea creature washed up on the beach. A team of researchers meet up with the creature and the same time as them, and Rich and Laura, along with the dead creature, are brought to a lab. Rich and Laura face an interrogation and questioning, while the researchers prepare for a possible autopsy on the creature, which is clearly a new breed.

Meanwhile, Miles tries to control Nimrod at a big party thrown by his sister. Nimrod just wants to get in on the action, but unfortunately, that's out of the question.

The phenomena becomes more widespread as similar creatures wreak havoc on the coast of Texas. Laura gets more upset after she loses her job, while Rich still has a difficult time getting over the loss of his brother. Rich's situation gets worse when he starts to hear his brother's voice when he is near water. Cirko and Lee find that the creatures have been digging under the ocean bed, which could link them to global warming. Meanwhile, Miles discovers that it's not safe to raise Nimrod in the backyard when lightning strikes.

Laura manages to fire a tracking device into one of the mystery creatures, allowing the researchers to track it on a radar. Rich, who has taken a break to deal with his brother's passing and the voice he keeps hearing, finds that letting go is harder than he thought.

Meanwhile, Aleksander Cirko attempts to convince the Pentagon and the government that the new creatures are predatory, extremely dangerous, and must not be approached by civilians.

Laura and Richard continue to track the sea creature tagged by Laura via the GPS device. All is going well until, oddly, a massive blackout darkens the city, destroyed much of the data Laura and Richard had amassed. Cirko and Lee, who have been following the pair for a while, decide the time might be right to extend an invitation...

Miles and his buddy Phil are questioned by the suspicious Animal Control officers and need to keep quiet about Nimrod through the interrogation. However, the officers suspect Miles is hiding something, and aren't going to give up easily.

While researching a sea orchid, Aleksander Cirko has an unexpected breakthrough and discoveries the mystery sea species' origins. However, he only has time to tell Lee before he is mysteriously hit by a car. The sea orchid is taken, and Ciko, badly injured, is left abandoned by the roadside.

Singh, Cirko's assistant, attempts to continue the work by reclaiming the orchid from a government warehouse. Singh needs to infiltrate a warehouse, grab the orchid and other important items, and leave. Will he be successful? Or will the mission fail?

Meanwhile, Rich and Laura both face problems of their own. Evidence says that Laura's house was ransacked, and she believes it was done by none other than the government itself.

Dr. Lee gives a small account of Cirko's passing to his superiors, concluding that it was a necessity in the long run, before revealing a new and budding clue in this investigation. Laura and Rich enlist the help of Jackson (Austin Nichols) when her home is mysteriously ransacked by strangers, sending the trio under the radar and up the coast. Meanwhile, Nim's uncontrollable behavior forces Miles and Phil to steal a pizza delivery car and lead the police on a chase to the beach where Miles lets Nim go in the ocean. Nim reluctantly swims away and Miles turns back to the shore where his parents and the police are waiting for him. Leighton Meester also stars

Laura, Rich and Jackson race to finish the submersible they are building, and despite several setbacks during a test run, take it out to the spawning site. As Rich and Daughtery begin their descent, they spot the creatures spawning, and prepare to gather their data. However, something goes wrong, and, due to a technical failure, the submersible begins to freefall down to the ocean floor, leaving the two oceanographers trapped on the seafloor with the air supply running low.

Elsewhere, Miles' parents consider sending him to a boot camp for problem children, hoping he'lll begin to straighten out what they believe is a crooked lifepath. Miles knows that if he is sent away, he will be seperated from Nimrod, who in turn will be lost without his caretaker. Miles can't allow that to happen.

It's a race against time as Laura and Rich race against time in a submersible they realize the 'unidentified species' are laying thousands of eggs on the ocean floor. Meanwhile, Miles hears a report of a vicious attack on a electrician working on a marine dock, and suspects that Nimrod may be the culprit. Elsewhere, Phil stakes out an underwater power cable in hopes of finding Nimrod only to discover Nimrod now has a lot of underwater friends.

When Laura and Rich return to the surface from the ocean floor, they realize the boat that took them to this location is nowhere to be found. Meanwhile, Miles is taken to the hospital after suspiciously passing out in class. Elsewhere, Miles' sister Savannah comes to the realization that her brothers sudden admittance to the hospital may have be a result of a bite mark on his body caused by his former pet Nimrod.

Rich and Laura sneak out of the hospital with the creature footage before Lee and his men can get to them. Upon their successful escape Rich and Laura take the exclusive footage to tape to a copying service company in an effort to upload it onto the internet and convince a news station to run a piece about the footage.

Meanwhile, Miles is sad and defeated while he watches doctors preparing to perform an autopsy on Nim but that all changes when Nim sneezes and they realize he is still alive.

Laura and Rich become fugitives and are being pursued by Lee and his legion of secret agents. While hiding out, Laura has a bizarre Internet exchange with a mysterious person who claims to have information about the origin of the creatures.

Meanwhile, Miles and Caitlin go to a bonfire party at the beach and are stunned when two of her friends mysteriously disappear after a late-night swim. The next day the Coast Guard makes a grisly discovery.

After it's revealed to Laura that a cadre of top scientists created this new species, she wakes up in a field after being drugged and Rich comes to her rescue. Fearing the end of the world, Laura and Rich are determined to find the mysterious corporation that funded this experiment gone awry, but nothing could prepare them for what they discover in an abandoned laboratory along the way.

Meanwhile, Miles joins Blum and his crew of aquarium workers on a boat excursion to find the egg field containing millions of unhatched creatures. Surprisingly, Miles later agrees to help law enforcement find Nim.

Rich and Laura go to see Lee for answers, and Lee winds up learning more than he would have ever expected. Concerned about the escalating violence she sees in Rich, Laura decides to pack it in and return home to see her son.

The townspeople grow increasingly fearful as Miles behaves more and more like Nim. After being attacked by a bully at school, Miles brutally retaliates, and an angry mob calls for him to be arrested.

With a tsunami approaching the coast, the residents of Wilmington find themselves under a mandatory evacuation. Among the mass exodus of people leaving for safety, Miles and his family scramble to make it off the island.

Meanwhile, Laura travels to North Carolina to find Rich, who has been arrested by military police at the mysterious laboratory. As employees hurriedly vacate the building, Rich is locked up in a cell and left to die.