Rusty Bucket is a pony that got injured at work. The doctor informs him that he will never be able to go back. Then he wakes up the next day to find that his cutie mark has disappeared. Her friends come over to try and cheer him up but to no avail.
Rusty Bucket then lives the next couple of months in a slum until he receives a letter from Twilight inviting him to come to ponyville. Now he will get to meet each of Twilight's friends as he gets closer and closer to discovering his new cutie mark.