It's the end of the world. A huge flood is coming, large enough to wipe out every creature on the planet. Luckily for Dave and his son Finny, a couple of clumsy Nestrians, a giant Ark has been built to save all the animals of the world. But as it turns out, Nestrians aren't allowed. Sneaking on board with the involuntary help of Hazel and her daughter Leah, a ferocious Grymp, they think they're safe until the curious kids fall off the Ark. Now the pair must learn to work together to brave the elements and survive the rising waters and hungry predators... it's definitely not going to be smooth sailing.