Animated fun with the lovable mule. Muffin the Mule keeps fit by skipping, and everyone wants to know how they can join in and get fit too. Team sport is the answer, so Muffin starts his own football team, Muffin's Mules United. During their first training session they realise they don't have a goalkeeper, so they try to persuade the fitness-shy Grace to go between the posts - but she's not keen on doing anything too strenuous.