Emma loves to visit Grandma Dolly and her animal sanctuary in the summer holidays. At home, Emma isn't even allowed a guinea pig. While staying with Dolly, Emma's grandmother is asked to take in Mississippi, the beloved horse of her friend, wealthy Mr Clipperbush who has passed away. Emma can't believe her luck when Grandma then gives her Mississippi - a horse of her own. But suddenly, there's trouble. Mr Clipperbush's long-lost nephew wants the horse back - and will stop at nothing to get his way. What can Emma do? Saving Mississippi means everything .