The Contents of that Briefcase Henry Opens in the Hit Series?
For much of season 5 of *Stranger Things*, the young Holly Wheeler and Max Mayfield are imprisoned in a realm of memories built from the recollections of the villain Henry. The search for an escape route in episode 6 forces them to witness again a defining event from Henry's youth—an event that could contain the means to overcome him for good.
Editor's Note: The following contains major spoilers for *Stranger Things* season 5, volume 2.
Unearthing the Secrets of the Cavern
When she finds Max in the psychic realm dubbed Camazotz, it becomes clear she is hiding out in a grotto that Henry strangely fears. An accidental discovery a viewing device found in Henry's old home helps Holly understand that the danger lies beyond the cave. Matching her view to the cut-out, she and Max suddenly fall into a abandoned tunnel.
They watch a young, eight-year-old Henry find an injured and paranoid man. When Henry tries to help, the man fires a gun, hitting him in the hand. Fighting for his life, Henry strikes the man down with a rock. "Is this what corrupted him?" Holly questions through tears. Essentially, yes, but the event went deeper than a simple act of survival.
Similar to other plot points of the final season, the significance of the mine shaft incident is detailed in the stage play Stranger Things: The First Shadow.
A Naval Mystery and A Spy's Mission
*The First Shadow* opens with the infamous Philadelphia Experiment, which reportedly teleported a vessel into a plane dubbed the Abyss. The ship was attacked, and the lone returnee was the captain, who returned in a catatonic condition with an entirely new blood.
The captain's son, the future Dr. Brenner, sought to replicate this dimensional breach in the Nevada desert. But a disloyal lab worker took experimental components to sell to the Russian agents, who were keen to start their version of the tests. This spy in the mine shaft is the one who stole the materials.
So, What's in the Case?
Based on what is known about the doctor's experiments, the case almost certainly contained vials of Captain Brenner's infected blood. As shown, Henry is wounded and bleeding. Exposure likely occurred upon opening the case, which triggered the origin of his telekinetic gifts—powers he would later pass on to the children under Brenner's care.
Another possibility, the box could have held strange particles that later made its way to the Hawkins lab, where it acts to anchor the mirror dimension. *The First Shadow* reveals that young Henry ended up in the Abyss, returning hours later fundamentally changed. Throughout the play, he battles the control of a malevolent force, much like how Will was possessed by the Mind Flayer in an earlier season.
The Power of Fear
The reason Henry avoids the cave linked to that memory shows how profoundly traumatic the event was for him. While he controls the collective consciousness and seeks to merge the Abyss into Hawkins, a piece of the scared boy remains. Fear is his tool, and the series is building toward a final confrontation between him and Will, who has deliberately faced his own deepest fears to become stronger.
This journey has neutralized a key tactic of Vecna. Crucially, Will now is aware of what Vecna himself fears, and this may grant a key upper hand in the series finale to come.