I thought I was starting to hate 'Stranger Things,' then 'The Massacre at Hawkins Lab' episode changed everything

• Warning: Spoilers ahead for "Stranger Things" season four, part two.
• "The Massacre at Hawkins" is a worthy conclusion to the first part of the new season.

Two weeks ago, the first six episodes of "Stranger Things" season four appeared in my Netflix press screening account. I watched them all that day.

I didn't like it.

The episodes felt bloated; stuffed with new characters I didn't really care about and rehashing of the same old problems. More cruel bullies with no apparent motivation other than cruelty. A big gross and scary monster who also has no apparent motivation other than being gross and scary.

But then the seventh episode changed everything. The revelations contained in that episode not only made me appreciate the two-part structure of extra-long episodes this season, but made my rewatch of seasons one through three way more interesting and fun.

'The Massacre at Hawkins' reveal is a worthy payoff to the long season

Before I pressed "play" on the seventh episode, I saw the timestamp of the episode's length. One hour and forty minutes long?! There was no way this episode could be good enough to justify its run time.

But it did.

Though my irritants were still present (the over-the-top bullies, Hopper's dragged-out imprisonment) — this episode cracked open the entire show's world-building and lore in a surprising way.

For the first six episodes, Vecna felt like a rote bad guy who didn't feel all that interesting to me aside from wondering how many millions were spent on the CGI budget this season.

Over the course of the seventh episode, we see Eleven's memory of what really happened the day all the other children were killed at Hawkins National Lab. She had assumed she was somehow responsible. But Dr. Brenner's "NINA" machine showed the truth: The orderly (played by Jamie Campbell Bower) who had been helping her was really 001 — Henry Creel.

Henry manipulated Eleven into helping him remove a device from his neck that inhibited his powers and kept him imprisoned at the HNL.

Once freed from the device, Henry proceeded to kill every guard, doctor, and child in sight — leaving (we presume) only Dr. Brenner and Eleven alive. Once she realized what Henry had done, Eleven chose to fight him rather than join his quest to "restore balance to a broken world." Henry describes himself as akin to a spider: "A predator — but for good."

Despite previously struggling with her powers, Eleven managed to defeat the extra-powerful Henry. She disintegrated him into the Upside Down, forging the first known connection between those worlds.

Henry's reveal makes so many previously confusing questions much more clear

Previous seasons of "Stranger Things" have included a lot of murkiness around the history of HNL and how Eleven was linked to the Upside Down. After seeing the first season, the only logical conclusion was that Eleven had accidentally encountered the Demogorgon while she was practicing spying on people in the Void.

But now we know that Henry Creel (AKA 001 or "Vecna") was the first child in Hawkins to display supernatural abilities. The source of his powers is unknown, but Henry had control over them at a young age. He killed his mom and sister, and then fell into a coma before waking up in the HNL under the control of Dr. Brenner.

"He did not just want to study me," Henry said. "He wanted more. He wanted to control. When Papa finally realized he could not control me, he tried to recreate me. He began a program, and soon others were born."

Eleven didn't forge the first connection to the Upside Down the day she escaped HNL in 1983. She forged it when she defeated Henry in a fight to the death in 1979.

Now everything that's happened with the Upside Down can be traced back to Henry, making scenes in earlier seasons much more compelling

The Henry reveal retools the understanding of the whole series, taking each season's villain from mysterious evil to one through-line story about a sociopathic wizard who draws his power from pain and a powerful teenage girl who draws her power from love.

Henry wants to kill Eleven because she poses the biggest threat to him. He also wants control over the real world, because he fancies himself a "good predator" who can "restore balance."

Eleven defeated the Demogorgon in season one. So Henry sent the Mind Flayer next. But she defeated that creature, too. In season three, Henry once again tried using the Mind Flayer — this time assembling a physical form made from dead bodies.

And now, in season four, we finally saw the man behind the curtain. Henry is hunting teens in Hawkins, likely to try and draw Eleven out of hiding, bringing her face to face with him once again.

I, for one, can't wait to see that battle.

"Stranger Things" season four, part two will premiere on July 1.