Monster High: Ghouls Rule unearths an old conflict between "Normies" and monsters - and things are about to get scary! For years, students at Monster High were warned that Halloween was a night to stay inside and avoid conflict at all costs. But Frankie and her friends discover that ghouls and "Normies" once loved to spend the holiday together! The ghouls decide to turn back the clock and use the night to celebrate their individuality and show that it's okay to "Be Yourself. Be Unique. Be a Monster!"

SKRM (Skultimate Roller Maze) is an annual tournament between Monster High and different monster high schools that consists of a roller derby of dangerous obstacles and mazes. Granite City High, a high school team of gargoyles and Monster High's oldest rivals, won the school crest after defeating them in SKRM, and with it taking the school spirit. This has resulted in the school literally beginning to fall apart, and due to the boys serious injuries after the tournament, they decide not to participate any longer. This prompts the ghouls to play SKRM in the boys place, and they suit up and begin training. However, the boys protest and claim SKRM is a boys sport only, and they won't help the ghouls train. This only pushes them to work harder, with the goal of making it to the championship game to defeat Granite City High.