When eight-year-old Kirstie finds a strange egg near her home, she has no idea what will come out. Part horse, part toad, part turtle, and part crocodile? Only Kirstie’s grandfather knows what it is: a water horse! While it is certainly the oddest-looking creature Kirstie has ever seen, it is also the gentlest. But soon, the unusual pet gets bigger. And bigger. And BIGGER. Will Kirstie and her family be able to keep their new pet or will he have to make a splash in someone else’s home?