Pennywise is awake, and It: Welcome to Derry's season finale opens with a sinister fog descending over the town. Derry's children are called into the high school auditorium by Pennywise, who puppeteers their principal's corpse before tearing off his head.
The understandably terrified kids are then shown the Deadlights (Pennywise's true, cosmic form). Later, Lilly, Marge, and Ronnie find the school plastered with missing posters.
They set off after Pennywise, who is riding a circus cart out of the town with the children floating behind. With his cage open, the monster intends to leave Derry, but is taking them with him for sustenance.
Dick Hallorann leads Leroy Hanlon and Hank Grogan to the missing Will, and chaos ensues on the ice. Pennywise drags Marge away, revealing that she will one day become Richie Tozier's mother. He was clearly named after the late Rich Santos and is shown in a picture that Pennywise somehow has in its possession. It turns out that "It" knows Richie and his friends are going to kill him, and we learn the killer clown exists in the past, present, and future at the same time.
Pennywise isn't sure whether Richie brings his death or birth (suggesting the creature survived It: Chapter Two), but plans to kill Marge to stop that eventual confrontation from taking place.
Fortunately, Dick uses his power to freeze the monster, as our heroes attempt to get the dagger to a nearby tree, where it can be used to lock Pennywise back in his cage: Derry. However, "It" fights off Dick and finds itself face-to-face with Shaw, whom the entity remembers from their past encounter. With that, the General becomes its latest snack.
Pennywise makes a run for it, but the dagger is planted, and the clown is forced back into the sewers. All signs point to a happy ending for It: Welcome to Derry's leads, though Marge theorises that "It" can travel through time and will now go further into the past to try and kill their parents. That's the set-up for Season 2, while Hallorann leaves town to work in a certain hotel (The Shining's Overlook Hotel).
The show ends by confirming this was only "Chapter One" of the story, and we later return to 1988 and Juniper Hill. The real Pennywise's daughter, Ingrid Kersh, walks into another patient's room, where she has hanged herself. We then see the young Beverly Marsh; this was the moment her mother died, but Ingrid tells her not to worry. After all, no one who dies here ever really dies...and that may include Pennywise!
Set in the world of Stephen King's It universe, It: Welcome to Derry is based on King's It novel and expands the vision established by filmmaker Andy Muschietti in the feature films It and It Chapter Two.
The cast is led by Taylour Paige, Jovan Adepo, Chris Chalk, James Remar, Stephen Rider, Madeleine Stowe, Rudy Mancuso, and Bill Skarsgård.
The series, from Warner Bros. Television and developed for television by filmmakers Andy Muschietti and Barbara Muschietti (It, The Flash) and Jason Fuchs (Wonder Woman), will debut on HBO and also be available to stream on HBO Max. Muschietti will direct four episodes of the nine-episode series.
All episodes of It: Welcome to Derry are now streaming on HBO Max.