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 Rich are in for another shock when they leave the ocean floor and return to the surface. Meanwhile, Savannah suspects that Nimrod's responsible for Miles ending up in the hospital.

As a massive tsunami heads for the east coast, Laura must save Rich by heading to North Carolina where Miles and his family are trying to escape with their lives.