In 1908, a young boy named Francis arrives at a travelling circus and takes in the sights. A carnival barker eerily approaches him, urging him to take a look inside the freak show, creepily cackling as he enters.

With strange, piano music playing throughout, the boy observes the various geeks and freaks. He then notices a dark corner of the tent, where an old man’s voice in the darkness urges him to come closer. With no one else around him, the man strikes a match to reveal an empty eye socket and his horribly emaciated form. Terrifed, the boy runs from the tent, running directly into his father, who scolds him for being “a sissy”. Quickly glossing over that, he gives him a slingshot he won at the fair for him. They leave, while a white clown carrying red balloons and a trumpet watches on.

As they drive home, their car breaks down. As the father repairs it, he’s asked to purchase some water from a group of Native American children running a stall by the side of the road. Francis is just short of the five cents he needs but trades his slingshot to a young girl when she takes an interest. The father notices the slingshot is gone but seems to brush it off.

Francis and the girl soon become friends and play together in the fields. Francis playfully runs into the woods, despite the girl warning him not to, and finds himself alone with no idea where he is. The old man from the freak show reappears, popping out from behind trees, before pouncing on him. Francis makes a run for it as the man turns into a bestial creature – pursuing him at speed on all fours.

When the girl saves him by nailing the creature in the eye with the slingshot, giving Francis enough time to run – but the creature does not give up the chase, and we cut away just as the creature lunges once more.

Back in 1963, Lilly’s mother comes to pick her up from Juniper Hill Psychiatric Hospital. Lilly has formed a bond with a kindly housekeeper, who teaches her how to properly make her bed, and assures her that things will be OK.

Lilly shares her guilt about Ronnie’s father, fearing she’d end up back at the hospital if she told the truth. The housekeeper says she believes Lilly, but some people will only believe in what they see. Nonetheless, she’ll find a way to make things right.

Over at the jail, Hank is visited in his cell by Chief Bowers, who acts friendly towards him by offering him a cigarette, but then informs him that a witness puts him near the scene of the cinema. Pressuring him to confess to killing the kids, Hank stays strong, insisting he didn’t do it. But Bowers tells him he knows he’s lying – producing a discarded pack of his favourite brand of cigarettes from his pocket, claiming they found it where the witness placed him at the time of the murders.

At school, Ronnie is dogged with dirty looks now her father’s been branded a child killer. She finds someone has scrawled “Hatchet Hank’s Gonna Fry” in lipstick on her locker. Ronnie tries to rub it off as the Pattycakes watch on in amusement, leaving her with red hands. In the bathroom, Lilly gives her rubbing alcohol to help her get rid of it, but Ronnie wants nothing to do with her, blaming Lilly for her dad being in prison.

Lilly promises to come forward and tell the truth but worries that everyone will think she’s crazy after her time at Juniper Hill – so she needs proof of what they’ve seen, suggesting they try to catch them on camera. Ronnie remarks they’d never be able to get them developed, so they set about trying to find someone who can.

At the Army base, the officers have investigated the car wreckage they found, noting that it was part of 1935 gang warfare, and nothing of note has surfaced that could lead them to the weapon they’re looking for. General Shaw says he’s not surprised, believing it’s not the beacon they want that will take them to their target, but that something must be around the car for Hallorann to be alerted to its presence. Shaw suggests putting him in the air to see if he can sense something.

At the soldier’s base, Hallorann and his friends are winding down with cigarettes andcard games, but are disrupted by the rain, which collapses the roof of their tent. Hallorann is called away, and the next morning Hanlon and Russo head to their plane for the surveillance flight. A cigar box is handed to Hallorann, and Russo later mentions it, but he refuses to disclose what’s inside.

It's revealed to contain the same slingshot owned by Francis that hit the creature – and Hallorann is using it as a kind of psychic compass.

Back in 1908, Francis escapes out of the woods with his friend and asks what it was they saw. She refuses to tell him.

In the present, the girl – revealed to be Rose, the owner of the Derry antique and second hand store – is meeting with the local Native American community to discuss the Army trying to encroach on their sacred land. The meeting sees them arguing over whether they’re trying to buy the land or not, but she’s distracted by the arrival of her nephew, who informs her the car the Army found used to belong to Al Bradley, and she needs to do something now.

She refuses, saying she doesn’t want to do anything until she knows what they’re doing out there.

Back on the plane, Hallorann falls into a trance while following the guidance of the slingshot. When he becomes unresponsive, Russo and Hanlon call base and ask to head back. Base refuses, and Hallorann starts walking around the ship.

In his vision, Hallorann finds himself locked in a wet, underground cellar, filled with discarded toys and playthings. Under a mountain of the items lies an old circus trailer marked with a “Pennywise” illustration. The side of the trailer comes crashing down, and he sees nothing but a pair of yellow eyes, and a voice asking who he is. He’s then beset with a series of terrifying visions blurring his time at war, a family home being bombed, and other horrific images.

His attention is then drawn to above the trailer and toy-heap, where several bodies are floating in mid-air. One, calls out to him - apparently his mother - who tells him to get out. Panicking, he runs to a door and attempts to use the turn handle to open it, but in reality he has manually opened the back of the plane and is perilously close to walking out to his death. Hanlon pulls him to safety just in time, snapping him out of it, but Hallorann is left shaken from the experience and taken to the infirmary.

The General later visits him, congratulating him on a job well done, but Hallorann is not so sure, and warns him that it may be best to let it be. The being was able to see him – and they weren’t supposed to be seen.

At a diner, young Will is hanging out with his new friend, Rich, when Ronnie bangs on the window to get his attention. She believes with his book smarts he may be able to process the film for them if she can get the photos. Will agrees, which shocks Rich, and leads him to assume Will has a crush on Ronnie.

General Shaw comes to visit Rose – revealing himself to be Francis from the flashbacks. He remarks that, until he returned, he had no memory of Derry or her, but things came rushing back once he was assigned and moved back. Rose remarks that Derry does that to people.

He tells her they are there for soil surveys to lay down waterpipes, but she doesn’t believe him, saying even if she did, the elders of her community are worried they would be interfering with sacred burial ground. Despite this, she says she’ll talk to them for him.

A flashback shows Rose and Francis at a creek shortly before his family moved away. She tells him that Derry ‘has a way to make people forget, even if they don’t want to’.

Up at Matty’s lookout point, Lilly, Ronnie and the boys talk about how to lure the monster back out to them. Rich – a Cuban American – talks about their folklore and how his people could summon vengeful spirits with candle-lit rituals in cemeteries.

That evening, at the Hanlon house, Hallorann joins Charlotte and Leroy for dinner, where they reflect on their time before Derry. Charlotte reveals she was an activist in the Civil Rights movement before they moved, but Leroy worried it would reflect badly on him in the military. Hallorann is intrigued but doesn’t push it too much further.

After dinner, Leroy asks Hallorann what happened in the plane, but he finds it hard to explain, only that he ‘sees what other people don’t’. Leroy confronts him after noting that Hallorann brought up his son by name, despite having never mentioned him before that point.

Feeling the same odd sensation in his brain as the night of the attack at the army base, Leroy deduces out that Hallorann was one of the men that attacked him, and tells him to stay out of his head. Hallorann comments that he saw no fear in his mind – even with a gun held to his head – so he does not have to worry. He wouldn’t be someone he’d ever want to mess with.

Meanwhile, Lilly, Ronnie, Will and Rich head to a graveyard and light candles in a bid to encourage the entity to reveal itself. Rich chants the Prayer for the Dead in Spanish, but the kids quickly catch on that he doesn’t know what he’s doing. Will slips up and admits he doesn’t believe Ronnie’s claims of supernatural “mumbo jumbo” but believes she believes it. Furious, Ronnie takes her bike and rides off with Lily in tow, leaving the the boys alone.

However, things quickly take an eerie turn when the candles blow out, and no matter how far the girls ride, the exit to the graveyard keeps getting further away. The ground beneath them begins to crumble, and they become haunted by the spirits of Matty, Teddy, Phil and Susie.

As they desperately try to snap photos of the spirits, the camera is repeatedly dropped and reclaimed. Will is left holding the camera in front of a desolate crypt. Seeing something inside, he goes in to investigate, the camera flashes just as something rushes towards him.

Miraculously, he escapes and apologises to Ronnie for not believing her. The group hug each other in relief before breaking into the high school to develop the camera. Soon pictures of what they’ve seen start coming into focus – pictures of Lily’s deceased friends.

But the biggest surprise comes from Will’s photo from the crypt… a clown.