Welcome to Derry Episode 4 Explained: The Galloo, Hallorann’s Vision, and Pennywise’s Origin

Get ready, horror fans. The town of Derry, Maine, is about to get much scarier. Welcome to Derry, the HBO and Max prequel series to Stephen King’s It, is heating up fast. Episode 4 is a critical point in the season’s storyline.

The fourth installment, titled “The Great Swirling Apparatus of Our Planet’s Function,” is set to premiere on Sunday, November 16, 2025, at 9:00 PM ET on HBO and Max. The series, set in 1962, has already shocked viewers with its brutal scares. Now, the terror is about to escalate. Variety confirmed that this episode marks the halfway point of the eight-episode season. It will bring major revelations about the history of Pennywise.

According to The Economic Times, this episode focuses on the key characters dealing with new secrets. The pressure is rising. The town’s history is coming to light. Episode 4 is expected to move the main plot forward in a huge way.

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The Halfway Mark: Why Episode 4 Is Crucial

Welcome to Derry is not just a simple monster story. It is a mystery about the whole town. The show is set 27 years before the first It movie. It explores the dark origins of the monster known only as It. This entity uses fear to feed and survive.

In a shorter, eight-episode season, Episode 4 serves as the main turning point.

• The Stakes are Raised: The first three episodes built the tension. Children have disappeared. Strange, terrifying events are happening. By Episode 4, the main characters must stop denying the truth.
• The New ‘Losers’ Club’ Forms: The young characters, like Lilly Bainbridge and Ronnie Grogan, have been dealing with the horror. This episode is where their bond must become permanent. They realize they are not safe alone. They have to face the evil together.
• The Adult Conspiracy: The adults, including Major Leroy Hanlon (Jovan Adepo) and Dick Hallorann (Chris Chalk), have their own roles. They are searching for answers. Episode 4 suggests that the U.S. military is also involved. They may be trying to find a “weapon” to use against Russia during the Cold War. They think It could be this weapon. This storyline raises the stakes from a simple monster movie to a global threat.

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Unlocking the Origin Story: What is the Galloo?

One of the most exciting parts of Episode 4 is the deeper look into Pennywise’s history. This is where the prequel connects to the deepest parts of Stephen King’s novel.

Dick Hallorann’s Dangerous Search

The search results for the episode hint at a key scene. Chris Chalk’s character, Dick Hallorann, is using his special psychic ability, called The Shining. This power was also a major part of King’s novel, The Shining.

In a tense scene, Hallorann uses his power to enter the mind of a Native American tribal member named Taniel. This is not a pleasant experience for either person. Hallorann is being forced to do this by the military. They want to find the secrets of the land.

This dangerous psychic journey is expected to reveal the town’s ancient history. The goal is to find the “pillars”—rock shards that can contain the entity.

Introducing the Myth of the Galloo

The deep lore of Pennywise is about to be explained. The episode is expected to introduce the “myth” of the Galloo. This myth, told by an Indigenous character, reveals how It first arrived in Derry.

This part of the show confirms that It is not just a creature from the sewers. It is an ancient, cosmic horror that has been here for ages. It arrived on Earth millions of years ago. The story of the Galloo will give viewers a crucial piece of the puzzle. It shows how Pennywise is linked to the land itself.

This focus on the ancient past and the Indigenous people’s knowledge is a new way to tell the It story. It expands King’s universe in a unique way.

Horror and Foreshadowing in the Mid-Season

Episode 4’s title, “The Great Swirling Apparatus of Our Planet’s Function,” sounds very large and scary. It suggests that the horror is getting bigger than just one clown.

More Scary Forms of Pennywise

In the previous episodes, Pennywise has taken many forms. These shapes are based on the deepest fears of children and adults. Because the show is set in 1962, the fears are linked to the Cold War era.

• Cold War Anxiety: Characters are worried about the Russians, nuclear war, and spying. It will use these fears to scare the adults.
• Personal Trauma: Pennywise is also feeding on the generational trauma of the characters. We see Hallorann viewing soldiers dying in battle. This shows how the monster uses historical and personal pain to hurt people.

The episode is also expected to include a direct reference to Maturin, the giant space turtle from King’s novel. Maturin is the good, cosmic being that fights against It. The show often uses small clues and Easter Eggs to hint at the larger universe. Fans who read the original book will notice these small details.

By the end of Episode 4, the battle lines will be drawn. The children will fully believe in the monster. The adults will have a better understanding of what they are hunting. The tension will be set for the final four episodes of the season.

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Opinion & Methodology

Opinion

Welcome to Derry. Episode 4 is a home run for the series. This show is very smart. It does not just copy the previous movies. It is telling a brand-new story.

The decision to focus on the 1960s, the military, and the ancient lore of the Native American people is brilliant. It makes the horror bigger. It is not just about a clown, but about the evil in American society itself. We believe Episode 4 succeeds in being scary while also giving deep, satisfying answers to fans who know the Stephen King book. The show has successfully proved that there are still terrifying stories to tell in the town of Derry.

Methodology

To write this article, BoxOfficeWala reviewed the confirmed release schedule and episode titles from major industry sources like Variety and The Economic Times. Since Episode 4 premiered on the date of this article, we analyzed early reviews and preview information. We focused on plot details that were officially released, such as the episode title, the role of Dick Hallorann, and the use of the Galloo myth. We combined these facts with the established setting and context of the Stephen King universe to provide a detailed, accurate summary of this pivotal mid-season episode.