From taking her to school to making her food to doing her laundry, Riley Henderson's brother Devin has always been there for her, but now he's in California attending a prestigious college gaming program, and Riley is stuck alone in Florida with her single mom. Fortunately, things start to look up when she befriends her new neighbor Lucy, and the girls learn they both love Dungeons & Dragons. When Lucy asks her to run a campaign, Riley isn't sure since her brother had always been the Dungeon Master, but she decides to give it a shot. The girls invite their neighbors, Hannah and Jen, to join them, and Riley starts to get the hang of things from being Dungeon Master to making her own snacks and dinner. But when Devin runs into trouble with his program and returns home, Riley realizes that she has flourished without her brother and that they both need to be more independent.