People all over the world experience bizarre encounters involving strange new creatures in the oceans. Among those people are Laura Daughtery, a marine biologist and single mother working in California, Richard Connelly, a Louisiana family man fishing in the Gulf of Mexico, and Miles Bennett, a North Carolina teen who finds one of the creatures' eggs.

After a mysterious animal carcass is discovered on the shore of Sullivan's Island, Laura and Rich head there to look for some answers but instead get detained for questioning. Also, a team of scientists face a hazardous autopsy of the deceased creature. Meanwhile, Miles decides to name his new discovery Nimrod but faces panic and trouble when Savannah throws a party at which point Nimrod ends up escaping.

Cirko's life is in danger after he discovers the origin of the mysterious new species. Laura and Rich begin to fear for their own safety when they come into possession of a much sought after sea orchid. Miles sneaks Nimrod out of the house when his parents realize that he's been secretly keeping the animal as a pet.

Jackson helps Laura and Rich build a submersible so that they can visit a site where the creatures spawn. Meanwhile, the Bennett's consider boot camp as a way to discipline Miles.

Rich and Laura try to get the footage of their trip to the ocean bottom to a news station before Lee can stop them. Meanwhile, Miles must watch as doctors prepare Nim for an autopsy.

On the run with Rich, Laura encounters a mysterious person who claims to know the origin of the creatures. Meanwhile, Miles fears the worst when two of Caitlin's friends vanish at the beach.

Laura and Rich decide that it's time to get some answers from Lee as Laura considers going back home. Meanwhile, Miles gets in trouble with the local residents after a violent incident with a bully.