Twilight, Spike, and their friends leave the School of Friendship to embark on another adventure. To fill in during their absence, Twilight assigned a substitute teacher to cover for her and teach her History of Friendship class. When the students find out they begin discussing what pranks they should pull or how they can convince what they assume will be a pushover substitute to go easy on the homework.

The pony who walks through the door is not who they were anticipating.