The Duffer Brothers have revealed that the upcoming Stranger Things spin-off will explore the mystery surrounding the stone Henry Creel found, which connected him to the Mind Flayer. While not directly about the Mind Flayer or Upside Down, this new mythology aims to answer lingering questions related to Henry's past. The creators confirmed the spin-off project in 2022, with production potentially starting soon, though an official release date remains unannounced.