What's Inside the Case Henry Opens in the Hit Series?
During the bulk of the concluding season of *Stranger Things*, the young Holly Wheeler and Max Mayfield are held captive within a psychic prison built from the recollections of the villain Henry. Their mission for freedom in the pivotal sixth episode forces them to witness again a life-altering moment from Henry's childhood—an event that could contain the key to defeating him once and for all.
Heads Up: This discussion details significant events for *Stranger Things* season 5, volume 2.
Unearthing the Secrets of the Cavern
When she finds Max in the world known as Camazotz, it becomes clear she is sheltering in a chamber that Henry strangely fears. By leaving the lens cap on a viewing device taken from Henry's old home allows Holly to realize that the source of fear lies beyond the cave. When she lines up her view through the cap, she and Max suddenly fall into a subterranean passage.
There, they witness a young, eight-year-old Henry find an man who is hurt and scared. When Henry tries to help, the man reacts violently, hitting him in the hand. To protect himself, Henry kills the man with a rock. "Did this make Henry evil?" Holly wonders aloud. It was a factor, but the event went deeper than a fight for life.
In keeping with mysteries of the final season, the truth about the encounter is detailed in the theatrical production Stranger Things: The First Shadow.
An Interdimensional Incident and Stolen Research
The play reveals the infamous Philadelphia Experiment, which transported a vessel into a realm dubbed the Abyss. It faced creatures, and the only one to return was the captain, who emerged in a vegetative state with an entirely new blood.
This man's son, Martin Brenner, attempted to recreate this phenomenon in the Nevada desert. One of his scientists stole research materials to sell to the Russian agents, who were keen to start their parallel research. The man in the cavern is that employee.
The Briefcase's Contents
Based on what is understood of Brenner's work, the briefcase most likely held some of the unique blood type. At that moment, Henry is wounded and bleeding. He likely becomes contaminated upon opening the case, which triggered the development of his psychic abilities—powers he would later pass on to the children in Hawkins Lab.
Another possibility, the container could have held dark matter that later made its way to Hawkins Laboratory, where it helps stabilize the Upside Down. The stage play explains that young Henry ended up in the Abyss, returning after half a day with a new blood type and personality. As a youth, he struggles with the influence of a sinister presence, similar to how Will was possessed by the Mind Flayer in the past.
A Weaponized Emotion
His lasting fear linked to that memory shows how utterly horrifying the encounter was for him. Even as 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 showdown between Vecna and Will, who has confronted his personal demons to fortify himself.
Will's growth has neutralized a key tactic of Vecna. Furthermore, Will now is aware of what his enemy truly fears, potentially giving him a key upper hand in the series finale that awaits.