The Mystery Within that Briefcase Henry Opens in Stranger Things?
For much of the fifth and final season of *Stranger Things*, Holly Wheeler and Max Mayfield are imprisoned in a realm of memories forged from the recollections of the villain Henry. The search for an escape route in the pivotal sixth episode forces them to experience a life-altering moment from Henry's childhood—a discovery that could contain the secret to his downfall for good.
Editor's Note: This discussion reveals crucial plot points for the concluding episodes.
The Discovery in the Cavern
After locating Max in the psychic realm known as Camazotz, it becomes clear she is taking refuge in a chamber that Henry avoids at all costs. By leaving the lens cap on a spyglass taken from Henry's old home helps Holly understand that the danger lies not within the cave. When she lines up her view with the shape, she and Max tumble into a subterranean passage.
They watch a child version of Henry encounter an man who is hurt and scared. Attempting assistance, the man fires a gun, striking Henry in the hand. In a desperate act of self-defense, Henry strikes the man down with a rock. "Did this make Henry evil?" Holly wonders aloud. The answer is affirmative, but the trauma involved more than a simple act of survival.
Similar to other plot points of the final season, the significance of the mine shaft incident was first explored the theatrical production The First Shadow.
A Naval Mystery and Stolen Research
*The First Shadow* opens with the legendary naval test, which transported a U.S. Navy ship into a plane dubbed the Abyss. The ship was attacked, and the lone returnee was the ship's commander, who emerged in a catatonic condition with an different blood composition.
That survivor's offspring, Martin Brenner, wanted to repeat this experiment in the Nevada desert. However, a treacherous employee stole research materials to hand over to the Russian agents, who were keen to start their own interdimensional projects. The man in the tunnel is that employee.
Unlocking the Mystery
Considering what is revealed about the doctor's experiments, the briefcase would assuredly have vials of the unique blood type. At that moment, Henry is already bleeding. Exposure likely occurred upon handling the contents, which triggered the awakening of his powers—traits he would genetically impart to the kids Brenner would experiment on.
Another possibility, the case could have held dark matter that eventually found its way to the Hawkins lab, where it maintains the stability of the Upside Down. The stage play explains that young Henry somehow wound up in the Abyss, returning 12 hours later with a new blood type and personality. From then on, he battles the influence of a sinister presence, much like how Will Byers was controlled by the Mind Flayer in an earlier season.
A Weaponized Emotion
Henry's enduring terror associated with the mine shows how utterly horrifying the incident was for him. While he orchestrates the army of monsters and works to collapse the Abyss into Hawkins, a piece of the scared boy still exists. Vecna uses fear, and the series is building toward a climactic battle between Vecna and Will, who has deliberately faced his personal demons to become stronger.
This journey has taken a weapon from Vecna. Furthermore, Will now is aware of what the monster's own weakness, potentially giving him a decisive edge in the series finale to come.