S5, E4: When Amy works with a chuck wagon horse she discovers an impediment that could put the entire team in danger and change the dynamics of a prominent chuck wagon family. Meanwhile, everybody at Heartland deals with sleep deprivation as Lou and Peter desperately try to get their baby to sleep at night. Mallory thinks she's found a solution, but her sleep training method ends up pitting Lou and Peter against each other. And Caleb surprises Ty when he returns home to the trailer from the West Coast... without Ashley.