What's Inside that Case Henry Unlocks in Stranger Things?
During the bulk of the fifth and final season of *Stranger Things*, the young Holly Wheeler and Max find themselves trapped in a realm of memories forged from the past of Henry Creel. Their mission for a way out in the pivotal sixth episode leads them to experience a traumatic incident from Henry's childhood—an event that may just hold the secret to his downfall permanently.
Spoiler Warning: The following reveals crucial plot points for the second part of the final season.
Unearthing the Secrets of the Cavern
Upon meeting Max in the psychic realm called Camazotz, Max reveals 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 lets Holly see that the source of fear lies not within the cave. Matching her view through the cap, she and Max plummet into a subterranean passage.
In this place, they observe a young, eight-year-old Henry encounter an wounded, fearful individual. As the boy offers aid, the man panics and shoots, hitting him in the hand. Fighting for his life, Henry ends the threat with a rock. "Did this make Henry evil?" Holly questions through tears. Essentially, yes, but the event involved more than a fight for life.
Similar to other plot points of the final season, the significance of the encounter originates in the live show Stranger Things: The First Shadow.
An Interdimensional Incident and Secret Science
This backstory explains the infamous Philadelphia Experiment, which allegedly sent a U.S. Navy ship into a plane later called the Abyss. Demogorgons assaulted it, and the lone returnee was the captain, who returned in a vegetative state with an entirely new blood.
That survivor's offspring, Martin Brenner, sought to replicate this experiment in the Nevada desert. But a disloyal lab worker stole research materials to sell to the Communist spies, who were desperate to launch their version of the tests. The man in the tunnel is that employee.
So, What's in the Case?
Given what is revealed about his research, the container would assuredly have vials of the altered blood. In the scene, Henry is bleeding from his hand. Exposure likely occurred upon handling the contents, which triggered the development of his psychic abilities—abilities he would later pass on to the children Brenner would experiment on.
Another possibility, the box could have held strange particles that later made its way to Hawkins Laboratory, where it acts to anchor the Upside Down. The prequel shows that young Henry was transported in the Abyss, coming back 12 hours later with a new blood type and personality. From then on, he fights the control of a malevolent force, reminiscent of how Will Byers was influenced by the entity in an earlier season.
Confronting Terror
His lasting fear associated with the mine demonstrates how utterly horrifying the event was for him. While he controls the collective consciousness and works to collapse the Abyss into Hawkins, a piece of the scared boy remains. Fear is his tool, and the show is setting up a showdown between him and Will, who has confronted his own deepest fears to become stronger.
His confrontation has taken a weapon from Vecna. Furthermore, Will now understands what the monster's own weakness, which could provide a key upper hand in the ultimate battle that awaits.