Poly is an abused pony who has become recalcitrant through bullying. He belongs to the menagerie of a traveling circus which, at the beginning of the story, is set up in Saint-Cyr-sur-Dourdan, where little Pascal lives. He is then 4 years old and comes to observe the preparations for the show he plans to attend that evening. He wanders near the caravans, opening his eyes sometimes curious, sometimes admiring, when suddenly, tragedy strikes, he sees a little defenseless pony mistreated by unscrupulous torturers. Then, an idea comes to him, to allow the pony to escape! He succeeds and helps him hide, aided by the children of the village who build him a shelter, heal him and feed him. Pascal will then live with his pony a great story of friendship full of adventure.