S4, E14: Amy helps Stuart Forest, the trainer of the horse that got Amy a ton of hits on Youtube for being a "Miracle Girl". His daughter Rihanna's horse is too much for Rihanna to handle but he won't accept that. Chase tries to help by giving Rihanna a new bit, but she is too eager to make her dad proud and has an accident. Stuart then decides to sue Heartland for negligence. Peter is being sued and is bankrupt. Meanwhile, Jack is trying to persuade Mallory to come back to Heartland and care for Copper. Caleb returns without Ashley.