The world is about to be submerged by the Great Flood, but luckily an ark has been built to hold all the animals. All except Dave and his son Finny, a couple of clumsy Nestrians, who can't get in because they are not on the list of the boat's captain, the vain and merciless Lion. They decide to sneak aboard thanks to the involuntary assistance of Hazel and her daughter Leah, two Grymps. Everything seems to be going smoothly until Finny and Leah fall off the Ark due to a giant wave and are left to the mercy of the flood and hungry predators. Dave and Hazel will have to set aside their differences to try to rescue their respective children.
