May Goes to England

Wild ponies aren't the only creatures living in the English countryside
May and her family are traveling to England for vacation. She's going to miss her friends the Pony Tails and her pony Macaroni, but she can't wait to start exploring. May's big sisters, Ellie and Dottie, have been telling her stories about the pesky piskies of Cornwall—mischievous spirits who cause trouble. But luckily, Cornwall is also home to wild ponies, and May is determined to see one. 
But when the girls head out to look for them, Ellie gets hurt. Could this be the work of the piskies?