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.

Laura and Jackson head out to sea where she ends up using a GPS device to track one of the creatures. Rich finds proof that the sinkholes in his visions are real causing him to continue obsessing over his brother's death. Meanwhile, Lee tries to talk Cirko out of telling the Pentagon that the new species should be considered extremely dangerous.