The Contents of that Briefcase Henry Opens in the Hit Series?
During the bulk of season 5 of the popular Netflix show, Holly Wheeler and Max are held captive within a psychic prison forged from the recollections of the villain Henry. Their quest for a way out in "Escape from Camazotz" has them experience a defining event from Henry's early years—a discovery that may just hold the secret to his downfall permanently.
Spoiler Warning: This discussion contains major spoilers for the second part of the final season.
The Discovery in the Cavern
Upon meeting Max in the world dubbed Camazotz, Holly discovers she is hiding out in a grotto that Henry is terrified of. An accidental discovery a spyglass taken from Henry's old home helps Holly understand that the true terror lies beyond the cave. When she lines up her view with the shape, she and Max plummet into a subterranean passage.
They watch a Henry as a boy encounter an wounded, fearful individual. Attempting assistance, the man reacts violently, striking Henry in the hand. Fighting for his life, Henry strikes the man down with a rock. "Was this the turning point?" Holly asks tearfully. Essentially, yes, but the event involved more than a fight for life.
Like many elements of the final season, the full story behind the mine shaft incident is detailed in the theatrical production Stranger Things: The First Shadow.
The Philadelphia Experiment and Secret Science
This backstory explains the legendary naval test, which allegedly sent a U.S. Navy ship into a dimension later called the Abyss. It faced creatures, and the only one to return was the ship's commander, who returned in a vegetative state with an altered blood type.
The captain's son, the future Dr. Brenner, wanted to repeat this experiment in remote Nevada. But a disloyal lab worker stole research materials to give to the Russian agents, who were keen to start their own interdimensional projects. This spy in the tunnel is the one who stole the materials.
The Briefcase's Contents
Given what is understood of Brenner's work, the briefcase would assuredly have some of Captain Brenner's infected blood. In the scene, Henry is wounded and bleeding. Exposure likely occurred upon handling the contents, which triggered the development of his psychic abilities—abilities he would later pass on to the children in Hawkins Lab.
Another possibility, the case could have held dark matter that was destined to travel to Hawkins Laboratory, where it maintains the stability of the parallel world. *The First Shadow* reveals that Henry ended up in the Abyss, returning after half a day fundamentally changed. Throughout the play, he battles the whispers of a sinister presence, similar to how Will was influenced by the shadow monster in season 2.
The Power of Fear
The reason Henry avoids the cave of that cave shows how utterly horrifying the event was for him. While he commands the army of monsters and attempts to pull the Abyss into Hawkins, a fragment of his psyche still exists. Vecna uses fear, and the show is setting up a final confrontation between Vecna and Will, who has deliberately faced his own deepest fears to become stronger.
Will's growth has neutralized a key tactic of Vecna. Furthermore, Will now knows what the monster's own weakness, and this may grant a critical advantage in the ultimate battle that awaits.
