The Contents of that Case Henry Opens in Stranger Things?
For much of the concluding season of the popular Netflix show, Holly Wheeler and Max Mayfield are held captive within a psychic prison constructed from the memories of the villain Henry. Their mission for an escape route in episode 6 leads them to relive a traumatic incident from Henry's childhood—a moment that may just hold the key to defeating him permanently.
Spoiler Warning: The following reveals crucial plot points for the concluding episodes.
A Journey Into the Cavern
After locating Max in the mental landscape called Camazotz, Max reveals she is sheltering in a chamber that Henry is terrified of. By leaving the lens cap on a spyglass found in Henry's old home helps Holly understand that the danger lies outside of the cave. Matching her view to the cut-out, she and Max plummet into a deep mine shaft.
They watch a young, eight-year-old Henry come across 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 kills the man with a rock. "Was this the turning point?" Holly wonders aloud. It was a factor, but the trauma wasn't just a defensive killing.
Like many elements in volume 2, the truth about the mine shaft incident is detailed in the theatrical production Stranger Things: The First Shadow.
An Interdimensional Incident and Secret Science
The play reveals the legendary naval test, which transported a vessel into a realm later called the Abyss. The ship was attacked, and the only one to return was the ship's commander, who returned in a unresponsive state with an different blood composition.
This man's son, the future Dr. Brenner, attempted to recreate this experiment in the Nevada desert. However, a treacherous employee pilfered lab samples to give to the Soviets, who were keen to start their own interdimensional projects. This spy in the cavern is that employee.
So, What's in the Case?
Based on what is understood of Brenner's work, the container almost certainly contained samples of the altered blood. At that moment, Henry is already bleeding. He likely becomes contaminated upon contact with the blood, leading to the awakening of his powers—abilities he would inadvertently transfer to the test subjects Brenner would experiment on.
Alternatively, the container could have held dark matter that later made its way to the secret facility, where it maintains the stability of the mirror dimension. *The First Shadow* reveals that Henry somehow wound up in the Abyss, reappearing 12 hours later as a different person. As a youth, he battles the influence of a dark entity, reminiscent of how Will was controlled by the shadow monster in season 2.
Confronting Terror
The reason Henry avoids the cave of that cave shows how utterly horrifying the event was for him. While he commands the Hive Mind and seeks to merge the Abyss into Hawkins, a piece of the scared boy lingers. Vecna uses fear, and the show is setting up a showdown between him and Will, who has overcome his personal demons to fortify himself.
His confrontation has neutralized a key tactic of Vecna. Furthermore, Will now knows what the monster's own weakness, which could provide a key upper hand in the ultimate battle to come.