Granny's hunt for the perfect pet brings some unexpected results in this goofy adventure of family, mudlarking and mayhem. Zac and Essie have been helping their Granny Mo in her search for the perfect pet. She's tried everything from cats to axolotls and just can't find the right one.

But when the trio go mudlarking in the river bank they find a creature unlike anything else ... Granny Mo might have set out looking for a pet but now she's got a monster on her hands, and it's about to get up to some mischief!