Pine Hollow is quarantined by a suspected outbreak of equine influenza. Lisa has to bring Diablo in to establish if he is the source of the outbreak.
A mystery pony appears at Pine Hollow and follows Carole everywhere, which is a good thing since it saves her life.
When Veronica removes Trouble from the stables, she upsets the miniature donkey and his companion Danville Duchess, who escape on a cross country adventure. Only Jess and Melanie's detective work can find the donkey.
