🔗 Share this article

Throughout a large portion of the fifth and final season of *Stranger Things*, the young Holly Wheeler and Max Mayfield find themselves trapped inside a mental fortress built from the memories of the villain Henry. Their quest for an escape route in the pivotal sixth episode leads them to experience a defining event from Henry's childhood—a moment that potentially carries the means to overcome him permanently.

Spoiler Warning: This article contains major spoilers 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 sheltering in a cave that Henry is terrified of. A clever observation a spyglass taken from Henry's old home helps Holly understand that the source of fear lies outside of the cave. When she lines up her view through the cap, she and Max tumble into a subterranean passage.

There, they witness a child version of Henry come across an injured and paranoid man. Attempting assistance, the man fires a gun, striking Henry in the hand. In a desperate act of self-defense, Henry strikes the man down with a rock. "Is this what corrupted him?" Holly questions through tears. It was a factor, but the event went deeper than a fight for life.

In keeping with mysteries this season, the full story behind the encounter was first explored the stage play Stranger Things: The First Shadow.

The Philadelphia Experiment and Stolen Research

*The First Shadow* opens with the 1943 event, which transported a U.S. Navy ship into a dimension later called the Abyss. It faced creatures, and the only one to return was the ship's commander, who came back in a unresponsive state with an different blood composition.

This man's son, the future Dr. Brenner, sought to replicate this experiment in remote Nevada. But a disloyal lab worker pilfered lab samples to sell to the Soviets, who were keen to start their own interdimensional projects. That traitor in the tunnel is the one who stole the materials.

Unlocking the Mystery

Given what is understood of the doctor's experiments, the container would assuredly have samples of the altered blood. In the scene, Henry is wounded and bleeding. It's probable he was infected upon handling the contents, causing the origin of his telekinetic gifts—abilities he would inadvertently transfer to the kids Brenner would experiment on.

A second theory, the container could have held exotic matter that eventually found its way to the secret facility, where it helps stabilize the Upside Down. The stage play explains that the boy somehow wound up in the Abyss, returning hours later fundamentally changed. Throughout the play, he battles the whispers of a sinister presence, similar to how Will was possessed by the shadow monster in season 2.

Confronting Terror

The reason Henry avoids the cave of that cave demonstrates how utterly horrifying the incident was for him. Even as he commands the army of monsters and attempts to pull the Abyss into Hawkins, a piece of the scared boy remains. Vecna uses fear, and the show is setting up a climactic battle between the monster and Will, who has deliberately faced his personal demons to fortify himself.

His confrontation has effectively disarmed Vecna. More importantly, Will now knows what Vecna himself fears, potentially giving him a critical advantage in the endgame conflict that awaits.