Stranger Things 5 part 2 gives a new clue for why Henry is scared of the cave (but there's more to the story)

Who’d have thought going into the final episodes of Stranger Things that one of the biggest mysteries to come out of the season would involve the question of why Henry Creel is scared of a cave? But that’s quickly become the case as the mystery has become one of the biggest mysteries in the season leaving fans to wonder what happened to Henry at the cave. 

In the fourth episode of the show, we learn that Max has been trapped in Henry’s mind and has taken shelter in a cave which has become her sanctuary. As Max explains to Holly, there is something about the cave and the memory it’s connected to that terrifies Henry so much, that he refuses to enter the cave.

Outside of explaining Henry’s fear of the cave, no context is provided as to why he’s so afraid to enter the cave, but part 2 gives fans a new clue as to the origin of Henry’s fear – though there is more to the story  than the show fully explains. 

Warning: Spoilers ahead for Stranger Things season 5 part 2

What happened to Henry in the cave? 

In the first part of Stranger Things season 5, we learn that something happened to Henry in the cave which traumatized him so much he refuses to enter the cave and confront the memory. In the sixth episode of the season, “Escape from Camazotz,” we finally get a bit more context into what happened to Henry in the cave. 

While exploring the area outside the cave, Holly pulls out the looking glass she had taken from Henry’s room at Creel House and once again notices the cap on it. She gets frustrated at first, but then realizes that the cutout in the cap of the looking glass matches the shape of the cave opening. This leads Holly to the theory that the cave is part of a map and if they can line it up correctly, they can find a way out. 

Her theory proves correct as she literally stumbles upon an opening in the ground which leads down to a tunnel under the cave that looks like an old mine shaft. The pair make their way down into the mine shaft, and they hear a voice crying out in fear. This is when they see a mysterious man on the ground with a briefcase in one hand and a gun in another.

Holly and Max watch as the memory unfolds with a young Henry entering the cave and trying to explain to the man that he lives in the area, heard a scream and came to help. The man seems paranoid as he shouts to Henry and questions who sent him. Henry tries to ease the man's mind and assure him he's just there to help which is when the man shoots Henry in the hand, the pair then struggle for the gun before Henry bashes the man’s head in with a rock, killing him. 

Max and Holly run off, but Holly glances back on their way out of the memory to see young Henry opening up the briefcase but fails to show what’s inside. 

This moment provides some clarity on why Henry is afraid of the cave, but doesn’t give the full context just yet. Thankfully, The First Shadow Broadway play fills in some of those blanks for us. 

In the play, we learn that Henry was transported to Dimension X as a child when his family was living in Nevada. In the cave, Henry stumbles upon technology which had been stolen from Brenner’s lab by a Russian scientist. This technology transports Henry to this other dimension, where he encounters the Mind Flayer. 

This cave is connected to the moment when Henry’s world was changed forever, and it’s one of the most traumatic experiences in his life, thus why he’s afraid to revisit the memory and enter the cave. 

The moment Max and Holly observe in the mine shaft is the beginning of this memory when Henry comes across the Russian scientist, and the contents of the briefcase are what led him to Dimension X. It’s unclear if we’ll get to see this fully play out in the series finale, but at least we have The First Shadow to give us a bit more context until that moment arrives.