Full spoilers for the season premiere of IT: Welcome to Derry follow.If you thought IT: Welcome to Derry was going to rehash the Losers Club of the movies by following a group of kid protagonists as they survive their childhood encounter with Pennywise, traumatized but alive, then the ending of the season premiere put a quick and definitive end to that notion.Their investigation into the disappearance of local kid Matty Clements (Miles Ekhardt) leads Lilly (Clara Stack), Teddie (Mikkal Karim-Fidler), Phil (Jack Molloy Legault), and Phils little sister Susie (Matilda Legault) to the Derry movie theater, where Ronnie (Amanda Christine) shows them The Music Man, the movie Matty had snuck in to watch the night he went missing. Lilly and Teddie are both wrestling with guilt over not doing more to help Matty when they had the chance, but Phil tells them what matters is that theyre trying to do something now.It: Welcome to Derry, Episode One Ending ExplainedLilly recognizes the song Ya Got Trouble from The Music Man as the one that was playing when she thought shed heard Matty. Thats when Matty appears on the screen, trapped inside the movie. They cry out to him, instructing him to follow their voices so they can get him out. But Matty, who is holding a baby wrapped in a blanket, castigates them for lying to him and not being there for him. Theyre the reason why hes trapped in the movie to begin with, he says.The movie slows down, the image darkens, the song warps, and Matty looks up at them with an evil grin as the baby hes holding leaps out through the movie screen and into the real world. Its the Pennywise flying demon baby that killed Matty at the beginning of the episode, and now its loose inside the theater.The film negative burns and distorts on the screen as the flying demon or, as Phil calls it, a giant fucking mutant baby attacks Teddie, Phil, and Susie while Lilly hides under the seats. The monster picks off Teddie first, thrashing him about and smashing his head into the ceiling. His blood splatters down on Lilly, and his lifeless body is slammed into the projection booth window as a horrified Ronnie looks on, locked inside the booth and unable to help them.The monster then nabs Phil as Susie crawls on the ground toward Lilly. Give me your hand, Lilly instructs her just as the demon lands above her. A hammer-wielding Ronnie, meanwhile, escapes from the projection booth and rushes into the theater to find a blood-splattered Lilly. Theyre all gone, she mutters as the demon reappears and they flee into the lobby, Ronnie using the hammer to bar the doors behind them.What do you mean theyre all gone?! What happened?! Ronnie asks her just as Lilly looks down to realize shes holding Susies severed hand. Lilly lets loose a shriek that then transitions into the Nelson Riddle song Lolita Ya Ya as the end credits play. (That tune is from the 1962 film Lolita, directed by Stanley Kubrick; Riddle would later compose the iconic theme song for the 1960s Batman TV series.)Andy Muschietti on Killing Off the Shows Would-Be Losers ClubI recently chatted with Welcome to Derry executive producer Andy Muschietti about the season premiere and the choice to kill off most of the lead kids at the end of the first episode, and whether that was meant to make it clear to audiences that Welcome to Derry wasnt going to be a rehash of the IT movies.Muschietti, who directed the IT movies and the season premiere of Welcome to Derry as well as The Flash, said killing off Teddie, Phil, and Susie was a narrative device to basically get people in that mindset where no one is safe in this world, even clearly the ones that you're going to follow over the rest of the show. So yeah. It was also like kicking the chin, that unexpected thing that will hook the audience into wanting to keep watching, probably.Muschietti also spoke about the idea of birth horror present in the show, especially in the form that Pennywise takes in this episode.I think there's a very tight link to one of the themes of Stephen King's book. For people who read the book, the Losers, when they come back 30 years later, they all realize that they don't have kids, in their 40s, none of them have kids, and probably will never have. And that's a way of saying that these guys are subliminally terrified of bringing kids into this horrific world, Muschietti explained. And it's one of those lingering questions. It's never really solved. In the book, it's all questions that are, most of which are never answered, but it makes you think about it. And I think that's one of the themes, and that's why the baby thing is a recurring thing, and birth is a horrific event [that] is brought [up] over and over.Muschietti continued, The other side of the equation of that particular scene is the fears of the era. This is 1962, and America is in the middle of a Cold War, and there's a threat of nuclear attack. And all the kids know that.They're terrified because there might be a big bang anytime soon, and they're instructed to go under the tables in case of an attack, which is ridiculous. But that's one of the fears of the era. And birth defects, radiation was one of the things. I took that and combined it with the idea of the horror of birth, and that's how the scare was created.DC Comics Easter Eggs?Finally, eagle-eyed DC fans shouldnt read into the significance of Teddie reading Detective Comics #298, the first appearance of the second Clayface, Matt Hagen, though you could be forgiven for thinking that it was intentional, as Clayface is, like Pennywise, a shape-shifter.No, no. It was just the inclusion of the world of DC, which is very close to my heart, and I wanted to include it. Because we put Flash on the previous scene, there's an issue of Flash, then we included one that was Detective Comics, but it wasn't intended. It wasn't because of Clayface. It was just an issue of 1962 that I happened to think it was very appropriate, Muschietti said. I can't remember now, but I'm a hundred percent sure that our props master brought that with that intention.For more coverage, read our IT: Welcome to Derry season premiere review, which Tom Jorgensen gave a score of 8 out of 10, writing: The first episode accomplishes its most important task of re-establishing Derry and Pennywise with style and some expertly-drawn out tension, though some of the more CG-heavy scares fall flat. Indirectly honoring a popular critique of the novel, the kids side of the story is (so far) way more compelling than the adults, but Pennywise has barely begun to poke his red-tufted head out of the sewer, so theres plenty of time for that storyline to start floating.