Anni has recently moved with her family to the tranquil village of Great-Hottendorf and dreams of finally getting her own long-awaited horse. But her wish remains unfulfilled: Her parents have their hands full with other things. On top of that, she has to put up with teasing from Pia and Bine at her new school. She finds comfort in Lorenz, a boy of the same age who lives on the farm of his uncle Pieter and with whom she becomes friends. One day, when she seeks refuge in the nearby forest, she can’t believe her eyes: standing before her is a real untaimed horse, even with a heart-shaped pallor on its forehead! Between Wild Heart and Anni there is immediately a magical, intimate connection. But then horse thieves show up and want to steal and sell the herd where Wild Heart lives. Will Anni and Lorenz succeed in catching the thieves and bringing the untaimed horses back to freedom?