The Harry Potter series needs no introductions in the twenty-first century, but its contested theatrical sequel, Harry Potter and the Cursed Child, just might. Considered to be the only true medium to tell how the story progressed after the seventh instalment, this play is the most classical example of transmedia storytelling (sensu Jenkins). However, beyond its inflaming time-travelling plot, Cursed Child is both a complex exploration of generational trauma and the cornerstone of fantasy theatre, to the point where its aesthetics may be described as pre- and post-Cursed-Child Fantasy. This chapter centres on the exploration of how the Potter storyworld is recast in this theatrical sequel, illustrating the previously derided Slytherin house as a place of acceptance, and broadening the theoretical discussion of transmedia storytelling. Furthermore, the chapter inquires into how heightened immersion is achieved both through breaking various ontological boundaries between the play space and the audience—from characters descending the stage to redecorating the entire playhouse—and cross-generational relatable characters. Harry Potter and the Cursed Child takes genre reframing introduced with Wicked even further, mixing musical elements, science fiction, and fantasy to solidify theatre’s standing in multi- and cross-media popular culture.