Emma has come to spend the summer vacation with her grandmother, Dolly. She has a large farm: cats, dogs, parrots, fish, and an old gelding grazing in the pasture. Emma learns from her friends that Dolly's neighbor, old Clipperbush, has died. When Clipperbush's nephew, Alligator, tries to get rid of his uncle's beloved mare, Mississippi, Dolly buys her back and unexpectedly gives her to her granddaughter. But Emma's joy is premature: Alligator reappears and is trying with all his might to get Mississippi back. Emma and Dolly must save the horse at all costs!