Amy lives and breathes horses, but all her horses are in books or in her head. So when she goes on a picnic with her friend Hannah's family, Hannah thinks Amy is imagining things when she says she heard a horse neigh nearby. But then Hannah hears a neigh, too! What's a horse doing in the park?

With a little help from Mona at the Rainbow Street Shelter, Amy makes sure the horse is safe and sound. She almost hopes the owner never turns up, so that she could keep visiting the pony. . . .