Peter Kasimsiman was once a submissive son to his parents. But losing his mother at a tender age, left him with an abusive father who only knew of tending to his carriage horse, Brown Beauty. Peter is eager to win the love and attention of his indifferent Tatay. But an unfortunate incident forces him to run away from home. His horrible life starts to change its course when he meets the nurturing haciendera Helena who provides him shelter and unconditional affection he knew his father would never be able to give. Helena teaches Peter love and kindness, grooming him as the sole heir to the hacienda in the event of her death. Albeit fueled with the guidance of the good-natured foster mother, who's known for her passionate concern for her employees, Peter has an intolerable bad temper especially towards her mother's loyal servant, Maita and the latter's beautiful and gifted daughter, Samantha. Peter's almost perfect life is threatened as people from the hacienda adore the beauty and goodwill of Samantha. These include the estate's striking horse trainer, Erickson, the good-looking veterinarian, Dickson and even the trusted estate horse, Sylvester. Add the unwanted presence of his long-lost sister, Peter's life seemed like an everyday living hell. Little did Peter know that Diobayo, the Goddess of Horses, watches every move he makes as he grows oblivious to other people and the surrounding horses' needs. To teach Peter a painful lesson, Diobayo cursed him transforming him into the horse, Petra, whenever he acts surly and proud. Will Peter choose to continue his grumpy personality? Or will he be able to use his 'horse instinct' to change for the better?