March 28 (UPI) -- Netflix is previewing a documentary about the Stranger Things stage show that premiered on a London West End stage in 2023, and is arriving on Broadway Friday. Behind the Curtain: Stranger Things: The First Shadow arrives on the streamer April 15. Advertisement "It's a prequel that's set in 1959," a voice says in the trailer , released Friday, about the show. "And it tells a story of Henry Creel in Hawkins." In the Netflix series, Creel is the monster Vecna (portrayed by Jamie