Stranger Things is much beloved among critics and fans alike. While the series' penultimate season has yet to premiere on Netflix, early reviews are mostly positive. Some critics call the season a "horrifying" return to the once-quiet Indiana town of Hawkins. This could mean that great things are in store for horror fans who feel that the show's scares have petered out over the course of its three seasons.

While not a majority opinion, some fans believe that Stranger Things should have ended following its stellar first season. As Season 1 closes with the return of Noah Schnapp's Will, a host of spooky mysteries still loom. The disturbing horrors of the wicked Upside Down have yet to be revealed, and this lack of knowledge is what kept fans of macabre hooked, their imaginations running wild.

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Dr. Martin Brenner - Stranger Things Season 4

According to some, the mystery, scares and masterful suspense present in Season 1 were all but gone in the installments that followed. For most horror fans, terror lies in what audiences don't see. And since Stranger Things' ghoulish Demogorgans have stepped out from the shadows -- murdering the beloved and innocent Bob Newby in Season 2 and doing battle with the fearsome Eleven in Season 3 -- viewers felt that they'd seen it all.

Released on Twitter, the first eight minutes of Stranger Things' upcoming season promise a return to the series' horrific roots. Initially depicting the mundane daily life of the villainous Dr. Brenner, called "Papa" by Eleven, the sequence also reveals the fate of the assets that came before her. At the Hawkins National Laboratory, numerous children that share El's telekinetic abilities are shown, including a young boy called Ten.

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Stranger Things Ten

As Ten is cheerfully led to his next "lesson" with Dr. Brenner, the two pass a door with a numeral quite familiar to fans: 11. Viewers are also shown that Dr. Brenner's cold and horribly cruel nature wasn't always a facet of his character. Despite propping himself up as a father figure to Eleven, there was little fatherly love present in their relationship. This Brenner, however, playfully jokes with Ten, mocking his own artistic ability as the boy, with eyes closed, judges his drawing of a dog as a cow.

Ten's tests become more difficult. The boy is instructed to use his powers to peek in on the next room. It's here where the horror begins to play out. Far from a "normal" lesson, Ten observes that his fellow asset and another instructor are terrified and screaming. Racked with horror himself, Ten quickly reveals that both of them are dead.

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Eleven at Hawkins Lab in Stranger Things Season 4

The suspense builds, and soon whatever -- or whoever -- attacked the others goes after Dr. Brenner and Ten, killing the latter instantly. As an injured Dr. Brenner moves through the Laboratory, the blood-splattered dead cover the hallways. The friendly, bright imagery of rainbows and building blocks is juxtaposed with the mangled bodies of children.

As the first eight minutes of Season 4 draw to a close, both viewers and Dr. Brenner come to a horrifying conclusion. While Stranger Things fans have most certainly seen the attacker before, this reveal -- unlike others -- only enhances the horror. "What have you done?" Brenner asks, of an angry, rampaging Eleven.