Cody is an aspiring wizard who needs a familiar, but is hesitant to go through the official procedure. Fionna is his best friend, a closeted trans woman. She sees becoming a familiar as an easy way to get away from her family, which is far from accepting—not that she'd ever dare come out to them. Fionna's transformation kickstarts a series of realizations from the two friends and leads to Cody taking a deeper look into what makes up magic in pursuit of a new goal.