What's Inside that Case Henry Opens in Stranger Things?
During the bulk of the concluding season of the popular Netflix show, Holly Wheeler and Max are held captive inside a mental fortress built from the past of the villain Henry. Their mission for an escape route in "Escape from Camazotz" forces them to witness again a life-altering moment from Henry's childhood—an event that may just hold the means to overcome him for good.
Spoiler Warning: This discussion details significant events for the concluding episodes.
The Discovery in the Mine Shaft
When she finds Max in the world called Camazotz, it becomes clear she is hiding out in a cave that Henry strangely fears. By leaving the lens cap on a viewing device pilfered from Henry's old home allows Holly to realize that the true terror lies outside of the cave. Matching her view through the cap, she and Max plummet into a deep mine shaft.
There, they witness a young, eight-year-old Henry come across an wounded, fearful individual. When Henry tries to help, the man reacts violently, wounding the boy in the hand. Fighting for his life, Henry strikes the man down with a rock. "Is this what corrupted him?" Holly wonders aloud. Essentially, yes, but the act wasn't just a defensive killing.
Similar to other plot points in volume 2, the significance of the mine shaft incident is detailed in the theatrical production The First Shadow.
An Interdimensional Incident and Secret Science
*The First Shadow* opens with the legendary naval test, which reportedly teleported a warship into a realm known as the Abyss. It faced creatures, and the only one to return was the captain, who emerged in a catatonic condition with an different blood composition.
This man's son, the future Dr. Brenner, attempted to recreate this dimensional breach in Nevada. One of his scientists took experimental components to sell to the Communist spies, who were keen to start their own interdimensional projects. This spy in the cavern is that employee.
Unlocking the Mystery
Given what is revealed about his research, the container almost certainly contained vials of the altered blood. At that moment, Henry is wounded and bleeding. It's probable he was infected upon handling the contents, causing the origin of his telekinetic gifts—powers he would inadvertently transfer to the test subjects Brenner would experiment on.
A second theory, the container could have held dark matter that eventually found its way to the secret facility, where it acts to anchor the mirror dimension. The stage play explains that Henry ended up in the Abyss, reappearing hours later as a different person. From then on, he battles the influence of a sinister presence, similar to how Will Byers was controlled by the entity in the past.
Confronting Terror
The reason Henry avoids the cave of that cave shows how deeply scarring the event was for him. While he orchestrates the collective consciousness and seeks to merge the Abyss into Hawkins, a piece of the scared boy lingers. Fear is his tool, and the series is building toward a showdown between him and Will, who has deliberately faced his personal demons to become stronger.
His confrontation has effectively disarmed Vecna. Furthermore, Will now understands what the monster's own weakness, and this may grant a key upper hand in the ultimate battle that awaits.
