What's Inside that Briefcase Henry Unlocks in Stranger Things?

During the bulk of the concluding season of the popular Netflix show, the young Holly Wheeler and Max find themselves trapped in a realm of memories constructed from the memories of Vecna. The search for freedom in "Escape from Camazotz" has them experience a life-altering moment from Henry's childhood—a discovery that could contain the means to overcome him permanently.

Editor's Note: This discussion details significant events for the second part of the final season.

A Journey Into the Tunnel

Upon meeting Max in the psychic realm called Camazotz, it becomes clear she is taking refuge in a grotto that Henry is terrified of. By leaving the lens cap on a telescope found in Henry's old home lets Holly see that the true terror lies not within the cave. Matching her view through the cap, she and Max suddenly fall into a subterranean passage.

There, they witness a young, eight-year-old Henry encounter an man who is hurt and scared. Attempting assistance, the man fires a gun, hitting him in the hand. Fighting for his life, Henry kills the man with a rock. "Is this what corrupted him?" Holly asks tearfully. The answer is affirmative, but the event involved more than a simple act of survival.

Like many elements in volume 2, the truth about the mine shaft incident is detailed in the live show the prequel play.

An Interdimensional Incident and A Spy's Mission

This backstory explains the legendary naval test, which transported a vessel into a realm known as the Abyss. It faced creatures, and the sole survivor was the ship's commander, who came back in a unresponsive state with an entirely new blood.

The captain's son, Martin Brenner, sought to replicate this experiment in Nevada. One of his scientists took experimental components to sell to the Russian agents, who were eager to begin their parallel research. The man in the cavern was that very thief.

The Briefcase's Contents

Considering what is revealed about his research, the case almost certainly contained vials of the unique blood type. As shown, Henry is already bleeding. It's probable he was infected upon contact with the blood, leading to the origin of his telekinetic gifts—abilities he would later pass on to the test subjects in Hawkins Lab.

Another possibility, the case could have held strange particles that eventually found its way to the Hawkins lab, where it maintains the stability of the parallel world. *The First Shadow* reveals that young Henry ended up in the Abyss, coming back after half a day as a different person. As a youth, he fights the influence of a sinister presence, reminiscent of how the character Will was influenced by the Mind Flayer in the past.

Confronting Terror

His lasting fear of that cave demonstrates how utterly horrifying the encounter was for him. Even as he commands the Hive Mind and attempts to pull the Abyss into Hawkins, a piece of the scared boy still exists. Fear is his tool, and the show is setting up a climactic battle between the monster and Will, who has deliberately faced his own deepest fears to become stronger.

Will's growth has effectively disarmed Vecna. Furthermore, Will now understands what the monster's own weakness, and this may grant a critical advantage in the series finale ahead.