We're supposed to be trudging through the knee-deep waters of Pennywise's lair. Strapped up in galoshes, we're headed to the swampy underground of Derry, except when we get there the water has already been drained, little more than a thin layer of wetness clinging to the tunnel. With only a flashlight and the occasional burst of natural light creeping in from the grates and ladders build into the impressive structure, the tunnel is dark but you can make out enough of the details to get a thoroughly creepy vibe. But there is no water, and there is no It, and we, of course, are not in Derry, Maine but in Toronto, Canada on the set of Andy Muschietti's IT, where Stephen King's horror-fantastical world is coming to life on a soundstage.

But there's no water. and there's a bit of a to-do about it. After all, they didn't get us these swell boots for nothing. But production schedules shift, and no one minds a bit because holy hell, we're about to see the sewers of Derry, Maine realized in the flesh. On the outside, it's a construct of wood and plaster, craftsman notations and crew insignia scribbled on the walls, but inside... it's a creepy fucking tunnel where you might just find a killer clown/evil entity who loves to feast on children.

Walk down the tunnel for a bit, take a few turns, pass through some hefty round doors and you'll wind up in the cistern where It dwells. The walls are a crusted, rusty red-brown, lined with water demarcations.There's one really good puddle, which most of us make sure to walk through (we've got to put those rain boots to use somehow) and then, there it is -- Pennywise's lair.

At the bottom, you see Pennywise The Dancing Clown's circus wagon. It's a small, age-weathered room with slightly slanted floors and creaky-looking boards but it's what's outside it, above it, and around it that's truly creepy. Toys and small clothes and little children's shoes piled up in a cascading 30-foot tower; a jumbled trophy heap culled from It's kills, centuries worth of evil on display.

Not too far away, in another stage of the studio, Muschietti and his lead Bill Skarsgard are reinventing Pennywise. After we've had our fill of the cistern, we head over to observe filming where we see Skarsgard in his full Pennywise regalia -- orange hair jutting out in tufts around the pale pancaked face, with a pouty red blood mouth and razor-sharp teeth poking out. Unfortunately, we don't get to hear him talk. But we do get to hear him yip, bark, yell and a number of other strange utterances as the actor and director collaborate to create the perfect "Boo!" moment. The scene in question happens after the Losers research Pennwyise in a slideshow (taking the place of the photo album from the book) and the image of the killer clown comes to life, reaching out of the screen to prey on the children. Skarsgard's take on Pennywise is more animalistic than you might expect, and he offers his director a lot of options, shaking up his delivery and physicality with each new take.

To get the shot, Skarsgard is contorted, reaching through a small frame to sneer and snap at the children. Except there are no children, just a big camera, right in his face and between shots, Muschietti runs over to give notes, angling Skarsgard head up or down a little, twisting him to the side, looking for the scariest possible beat. They set and reset, time and again, and they're still not finished by the time we move on to the next portion of the tour, tirelessly seeking out the best scare.

In between touring the sets and observing production, I also joined a group of journalists to interview Muschietti, the cast, and some key members of the crew. We didn't get to speak to Skarsgard that day, who was needed on set, but we did get time with production designer Claude Paré, producer Barbara Muschietti, and the Losers Club -- Jaeden Lieberher (Bill Denbrough), Wyatt Oleff (Stan Uris), Jeremy Ray Taylor (Ben Hanscom), Sophia Lillis (Beverly Marsh), Finn Wolfhard (Richie Tozier), Jack Dylan Grazer (Eddie Kaspbrak), and Chosen Jacobs (Mike Hanlon).

• This movie is very R-rated. Despite the fact that violence towards children can be a no-go with the MPAA, the creative team didn’t have to hold back. The studio wanted the film to be R and that was the plan before the Muschiettis even came on board.
• The biggest difference between this script and Cary Fukunaga’s version in the emphasis on the shape-shifting nature of the entity in IT. “It was a good script, in terms of characters and the depth of characters and such, but it didn’t really tap into one of the most attractive traits of the character, which was the shapeshifting qualities.”
• The biggest things they inherited from that draft were the two-film structure, which follows the kids’ story in the first film and the adults in the sequel, and setting the film in the 80s.

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  They wanted to keep the 80s setting because they lived through that time period. “King writes what he knows, we try to film what we know. We grew up in the 80s. We wanted to do a very rounded 80s and not a caricaturesque 80s, and we can do that because we know the period very well,” said Barbara.
• Andy wants the sequel to have a “dialogue” with the first movie that would include flashbacks. The director explained, “I always insisted that if there is a second part, there would be a dialogue between the two timelines, and that it would be approached like the adult life of the losers, there would be flashbacks that sort of illuminate events that are not told in the first one.”
• They didn’t shoot those flashbacks while they filmed the first part. “No, I’m just praying that the kids don’t grow up,” Andy said with a laugh.
• They didn’t want to look at 20th Century clowns for Pennywise’s design, “Aesthetically, I don’t dig the 20th century clown. I think it looks cheap, and it’s too related to social events and stuff and circus and stuff, which circus is fine, but I’m more aesthetically attracted to the old time, like the 19th century clown," said the director.
• They had a huge audition process across the board, including older and younger actors, male and female.
• Tilda Swinton didn’t audition because she wasn’t available during the shooting slot but Barbara said, “Of course we thought about it!”
• Andy knew he wanted an actor who looks childlike but otherwise was looking for someone who would surprise him in any way.
• They did have a conversation with Will Poulter, who was signed on to play Pennywise in Fukunaga’s version, but he was gearing up for The Maze Runner and had a conflict.
• Muschietti had one sketch of the character and it looked like a warped Gerber Baby. “I had a sketch. One sketch. It was like a baby. It was like a Gerber baby. With something very off, because his eyes were wide-eyed - the eyes like, slightly apart. And then, to be honest, it didn’t evolve much from that point. And then the Pennywise you saw today is special because his hair is crazy, but the rest of the movie is different. I’m playing a little bit with his mood, and his mood sometimes in terms of the hair. There’s like two hairs maybe. But the official shape is more like a weird baby.”

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  Part of being a shape-shifter means that Skarsgard is performing a number of voices as Pennywise, depending on his persona. “He’s not sticking to one voice. He has different personas. Because it’s a character that is based also on unpredictability, so he has this stagey persona, the more clowny appearance, but then in certain scenes when he turns into this other, which is harder to grasp, and that’s the “other,” you know, the “It.” And he has a different tone, he has a deeper voice, and a different feel to it.”

• Obviously, they’re not doing the pre-teen sewer orgy.
• Muschietti isn’t diving too deep into the mythology of what brings the Losers together, so don’t expect to see or hear a lot about The Turtle. “I was never too crazy about the mythology, but it is mentioned, and the turtle appears, as a Lego. It’s a Lego turtle. It’s a presence that’s there in the key moments of the story,” Muschietti said. “It’s a bit of an Easter egg.”
• When Beverly sees blood in her sink, it's not a bubble's worth, it's a bloody geyser.
• There were two scenes that Muschietti had to cut for budgetary reasons, but neither were from the book. “[There] are two sequences that I thought of that I had to postpone until more money comes. One is a flashback, that sort of portrays the first encounter of It and humans, which is an amazing scene. And the other is a dream, where Bill sees— he’s leaning on a bridge, in Derry, and he’s spitting on the Kenduskeag Stream, and suddenly he sees the reflection of a balloon. And he looks up and it’s not one balloon, but a bunch of balloons, and then he starts to see body parts, and the shot goes wider and it’s a multitude of dead kids floating. I couldn’t afford it.”
• Don’t expect Pennywise to take the form of any pop culture icons. Instead, they wanted Pennywise to take on the form of “less tangible, more internal fears”. There will be winks to the 50s fears from the books, but as Barbara Muschietti explained, “he’s still very much in that sense a shapeshifter who basically tunes into a fear and will augment it and present it to you when you least expect it.”
• We only got one concrete example of what that could look like, but it sounds pretty fascinating. Muschietti explained, “The ones who are going to die in a fire in this adaptation are Mike’s parents. And this tragic event is directly in relation with his fear, which is a traumatic image of his parents dying. And he witnessed this as a baby, and it’s an image that’s in his head, and comes back when Pennywise basically incarnates and this image, which is white, abstract, it’s not a monster, it’s just an image. It’s terrifying.”
• It only takes his Robert Gray clown form at very specific moments, and they wanted to save most of his on-screen time for the third act. Barbara explained, “Very much like in the book, he appears as Bob Gray in very specific moments. We see him as little as we possibly can. That’s what we tried to do. But I think everybody will get their fair share of Pennywise if that’s what they’re going to the movie for.”

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  Asked about the difference between Tim Curry’s iconic take on the character and what they’re doing in this adaptation, Barbara explained, “You see Tim Curry and you already know that he’s an evil clown. There’s never a doubt about this. This Pennywise plays with his food. He taunts them, and that is of course very amusing but very disturbing at the same time, and very scary. I would say that’s one of the main differences.”

• This Pennywise apparently also has a lot of spit, meaning the kids would end up covered in prosthetic slime. The prosthetic teeth Skarsgard wears cause a drool build-up for the actor, so they've incorporated that element into the character.
• The Muschiettis did not resurrect the puppetry they used in Mama for their visions of Pennywise, but they did have a choreographer that worked with Bill on crafting a very physical performance. “We did not use the actual puppetry,” Barbara explained, “but we worked with Bill physically a lot and he is amazing and his structure — Yesterday, we were working on some scenes and there’s a great choreographer involved in our production and you will see him do some amazing things. This is a different, more active Pennywise.
• They did as much of the effects as they could practically and planned to use CGI for transitions or impossible sequences.
• Beverly’s bloody bathroom sink is a particularly sticky moment of gore. Poor Sophia Lillis and poor doubles,” Barbara said, referring to the intense blood rig they set up for the scene. “We do use some stunt doubles because we’re working with kids, but it’s practical. It’s all practical.”
• They kept the kids separate from Skarsgard as often as possible on set and din’t introduce them until the later weeks of the shoot.
• The actors playing the Losers spent weeks together ahead of production doing trust exercises, playing outside together, and basically learning how to be a kid in the 80s.
• Skarsgard based his performance as Pennywise on the things that scare him. “I only have my own senses to go on so I wanted to make something that I would be scared of. So an important thing for me in terms of preparing and creating the character was thinking “What are the things that I would find really unsettling?” And then explore that. Your own kind of fears and what you find disturbing and amplify that in terms of the performance. Essentially, what you’ll end up seeing in the film is my own deepest fears embodied in this character [laughs]”.
• The actor also put a lot of thought into playing a shape-shifting entity, “Obviously, it’s an extremely abstract character because the character is an entity taking the shape of a clown. I had to first figure out what the entity was and what the thing was that is taking the shape of the clown. The second step is to create the clown itself. I didn’t want the clown to be completely separate from the entity, right? I wanted It to really shine through Pennywise as opposed to just Pennywise being the clown. So a lot of what the entity is I wanted to be in the background of who Pennywise is at all times.”
• The house on 29 Niebolt Street was constructed in Oshawa, where it became a bit of an attraction for the locals.

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  The creepy tree outside the house was sourced from somebody's yard a crew member saw driving to set. They knocked on the door, negotiated for it, and transported the tree.
• Production designer Claude Pare originally pictured the sewers as being made out of brick, but it was too expensive.
• There is a giant Paul Bunyan statue -- about thirty feet high -- though they had to make some changes to the Bangor, Maine design to get clearance.
• The Muschiettis traveled to Bangor for a couple weeks to get a full sense of Derry's small town New England quality.
• They did not meet with Stephen King during the production or prep for the film. Barbara recalled, "He puts it very simply: The thing he loves the most is to write, and anything that keeps him away from sitting down at home and writing is not his favorite."
• The Muschiettis are not approaching the 80s with a nostalgic point of view, they want to keep it grounded and realistic. Barbara said, "You won't see the dreamlike Spielberg, Dante, the Super 8 [style]. It's grounded 80s, and this will sound a little naïve but we are not American, we are Argentinian. Our 80s are a little more toned down, not as exacerbated."
• She doesn't think people will find many similarities with Stranger Things beyond starring Finn Wolfhard and being set in the 80s.
• Barbara explained that they were looking for a "rarified" sound for the score. "It's not gonna be an 80-piece orchestra. We love things that get under your skin and really make your skin crawl. That is very necessary for this film."
• We won't see Pennywise's past, glimpses of what's behind the shape-shifting force of evil, or Derry's history of It-inspired tragedies play out on screen. But they think The Black Spot might make a great opening scene for the second film.
• The kids have a lot of fun thinking about who could play the adult versions of their characters. Some of the names thrown around included Chris Pratt for a grown up Ben Hanscom and Jessica Chastain for the older Beverly.
• Mike is more involved in the action and has a bigger role to play in the film than he does in the book.

Be sure to check out the brand-spankin-new IT trailer and for more of our coverage from the IT set visit, check out the links below and stay tuned for the full interviews:

• ‘IT’ Director Andy Muschietti Discusses the Changes from Cary Fukunaga’s Draft
• Don't Expect Much of Stephen King's Cosmic Mythology in The New 'IT' Movie
• The 'IT' Movie Had to Cut Two Crazy Scenes to Stay On-Budget