Ten-year-old Frances, known as Panky Poo, overweight and lonely after a move to the suburbs, becomes interested in a horse that needs her help and inadvertently overcomes her own problems.

Panky learns a great deal from training William, an unschooled pony, enough that she can accept inevitable changes when her father loses his job.

Panky thinks she is in love with one of the polo players at the club, but she doesn't like the way he and his friends treat their ponies.