Stranger Things Spinoff to Explain Briefcase Mystery

The creators of Stranger Things have announced that a new live-action spinoff series will resolve the mystery of the briefcase from the Season 5 finale. The finale revealed that a glowing rock found by a young Henry Creel was the catalyst for his transformation into Vecna. According to the creators, the spinoff will explain this origin story while introducing a completely new mythology and set of characters. The project is currently in development and is separate from the animated series 'Stranger Things: Tales From '85'.

The Season 5 finale of Stranger Things provided a definitive answer to the contents of the mysterious briefcase. In a scene set inside Henry Creel's mind, the series revealed that the briefcase contained a glowing rock. This rock contained Mind Flayer particles, which fused with Henry, allowing him to become one with the Mind Flayer. This event set in motion all subsequent events of the series. The scene also featured a warning from a dying scientist who stated, "It will consume you," and the Mind Flayer's beckoning call, "Come find me."

The origin of this rock is loosely explained in the canon play Stranger Things: The First Shadow. The play confirms that Henry and the scientist were transported to a dimension known as Dimension X in 1943. This transport occurred during a United States experiment intended to turn submarines invisible during World War II. It is implied that the mysterious rock originated in Dimension X and was brought back to the human world.

In an interview, Matt Duffer and Ross Duffer confirmed that the planned spinoff will address the briefcase rock. "The spinoff is going to delve into that and explain that, and you’re going to understand it," Matt Duffer said regarding the rock. However, the creators stressed that the series will not be a deep exploration of the existing Mind Flayer mythology. Instead, they described the show as a "clean slate" featuring a completely different mythology.

The creators outlined the scope of the new series:

• New characters: The show will feature entirely new faces.
• New setting: It will take place in a new town.
• New world: The narrative will explore a new world.
• No common characters: There will be no crossover with the original cast.

Matt Duffer described the project as "very fresh and very new," noting that it will answer some of the loose threads remaining from the original series. Based on the timeline of the briefcase events, the spinoff is likely to be set in the 1950s.

Netflix currently has two announced Stranger Things spinoffs in development. The live-action series discussed by the Duffer Brothers is the second of these projects. The first is an animated series titled Stranger Things: Tales From '85'. This series is set between Seasons 2 and 3 of the original show. It will follow the original characters as they fight new monsters and unravel a paranormal mystery in Hawkins. Tales From '85 is expected to be released sometime this year.