
Over the course of a winter, the beloved barn cat of Horseland, Mosey, is becoming very old and sick. Seen through flashbacks, the tale unfolds of his increasing illness and eventual death. All the riders, animals, and horses, especially Sarah, are heartbroken by his loss, and have trouble coming to terms with it.
When Alma discovers that her pen pal, Alexander, is going to visit Horseland, she's worried that she won't be good enough for him. Chloe and Zoey attempt to help her prepare to impress him, but their plan backfires. The two end up making amends and becoming friends at the end of the episode, after a landslide endangers Alexander.
When a new boy, Jesse, comes for an extended visit to Horseland, Bailey is overjoyed to have a boy his own age to hang out with. When he starts neglecting his friendship with Alma, Molly, and Sarah, though, tension grows. Chloe and Zoey, always jealous of his relationship with the other girls, go out of their way to ensure that much of his time is spent with Jesse. When Horseland is chartered for the Birthday party of the annoying Ethan Simon, though, the friends must get back together to organize the party.