What's Inside the Case Henry Opens in Stranger Things?
Throughout a large portion of the fifth and final season of *Stranger Things*, Holly Wheeler and Max Mayfield are held captive in a realm of memories forged from the memories of the villain Henry. Their mission for freedom in the pivotal sixth episode has them witness again a life-altering moment from Henry's early years—a discovery that could contain the means to overcome him permanently.
Editor's Note: This discussion contains major spoilers for the concluding episodes.
A Journey Into the Mine Shaft
After locating Max in the mental landscape called Camazotz, it becomes clear she is hiding out in a chamber that Henry avoids at all costs. A clever observation a viewing device found in Henry's old home allows Holly to realize that the true terror lies outside of the cave. By aligning her view with the shape, she and Max tumble into a subterranean passage.
In this place, they observe a child version of Henry encounter an man who is hurt and scared. As the boy offers aid, the man reacts violently, hitting him in the hand. Fighting for his life, Henry strikes the man down with a rock. "Did this make Henry evil?" Holly asks tearfully. The answer is affirmative, but the event wasn't just a defensive killing.
Similar to other plot points in volume 2, the truth about the mine shaft incident was first explored the theatrical production The First Shadow.
The Philadelphia Experiment and Stolen Research
This backstory explains the 1943 event, which reportedly teleported a U.S. Navy ship into a realm later called the Abyss. The ship was attacked, and the lone returnee was the ship's commander, who returned in a catatonic condition with an different blood composition.
That survivor's offspring, the future Dr. Brenner, attempted to recreate this phenomenon in Nevada. However, a treacherous employee pilfered lab samples to give to the Soviets, who were eager to begin their own interdimensional projects. That traitor in the tunnel is that employee.
The Briefcase's Contents
Given what is revealed about the doctor's experiments, the briefcase most likely held samples of the unique blood type. As shown, Henry is already bleeding. He likely becomes contaminated upon handling the contents, leading to the awakening of his powers—traits he would genetically impart to the test subjects in Hawkins Lab.
A second theory, the box could have held exotic matter that later made its way to the secret facility, where it helps stabilize the mirror dimension. The stage play explains that Henry ended up in the Abyss, reappearing 12 hours later with a new blood type and personality. From then on, he battles the control of a malevolent force, reminiscent of how Will Byers was influenced by the shadow monster in season 2.
A Weaponized Emotion
Henry's enduring terror linked to that memory demonstrates how deeply scarring the encounter was for him. While he controls the Hive Mind and seeks to merge the Abyss into Hawkins, a fragment of his psyche remains. Vecna uses fear, and the show is setting up a climactic battle between him and Will, who has deliberately faced his greatest terrors to gain strength.
His confrontation has effectively disarmed Vecna. Furthermore, Will now is aware of what Vecna himself fears, and this may grant a decisive edge in the ultimate battle ahead.
