Emma came to visit her grandmother Dolly for the summer holidays. She has a large farm: cats, dogs, parrots, fish, and an old gelding grazes in the pasture. From her friends, Emma learns that Dolly's neighbor, old Clipperbush, has died. When Clipperbush's nephew Alligator is about to get rid of his uncle's favorite mare Mississippi, Dolly buys her back and unexpectedly gives her to her granddaughter. But Emma rejoices early: the Alligator appears again and is trying with all his might to get Mississippi back. Emma and Dolly need to save the horse at all costs!