This is either the future of theatre, a bold IP cash-in or both. The play’s spectacular opening – a WW2 US battleship sent into another dimension – earns rapturous applause, heralding a video title sequence. The Duffer Brothers, Jack Thorne and Stephen Daldry know the show’s fandom and deliver a multimedia terrorfest which jumps between worlds, destroys the stage and mixes special effects at an ambitious scale. Set in 1959, it centres on a doomed school play directed by Joyce (Isabella Pappas, more than a passing resemblance to Winona Ryder), a spate of animal murders as Henry (Louis McCartney) is infested by growing powers and a comically inept investigation by a future Sheriff Hopper (Oscar Lloyd). Ella Karuna Williams steals it as Patty Newby, the Hawkins High School principal’s adopted daughter who nearly saves Henry through love. A prequel to the show’s fourth season, this may be a stand-alone tale, but you need to bring your lore. The gamble: is the fandom big enough to extend or export the show?