At the age of 21, Petra will transform into a horse. This is a fulfillment of the curse Silveria, the goddess of horses, put upon Kulas, Petra's father, after she caught him maltreated a horse. And the curse will only be lifted if Petra will do three heroic deeds.

The follow-up to Petrang Kabayo at ang Pilyang Kuting (1988) where a homosexual turns into a horse