Jessica Chastain, Bill Hader and James McAvoy get to know each other in the first behind the scenes photos from the set of IT: Chapter 2. The follow-up to 2017's blockbuster horror film IT takes place 27 years later as Pennywise the Clown returns to once again terrorize the town of Derry. Though they're all grown up and no longer remember their traumatic first encounter with Pennywise, the Losers' Club reassembles in their hometown to battle the ancient kid-devouring evil, and hopefully kill it for good.

Casting for the adult versions of the Losers' Club kids in IT: Chapter 2 has been a closely-watched process. First to join was two-time Oscar-nominee Jessica Chastain, who reunites with Mama director Andy Muschietti. The film later scored two more big name actors when James McAvoy and Bill Hader jumped aboard. Since then, the film has rounded out the Losers' Club with James Ransone, Andy Bean, Jay Ryan and Isaiah Mustafa. Bill Skarsgård of course returns to play the terrifying Pennywise. The kid versions of the Losers' Club are also expected to reappear in flashbacks.

Related: IT: Chapter 2: Jessica Chastain Starts Filming as Beverly Marsh

With IT: Chapter 2 officially underway, star James McAvoy has shared the first behind the scenes look at some of the assembled cast. McAvoy posted the Polaroids to his Instagram account, giving fans their first glimpse of what the actors look like together. See the image below:

McAvoy, Jessica Chastain and Bill Hader appear to already be working on their chemistry in the pic on the top right. The pic on the bottom left shows McAvoy getting to know actor Jaeden Lieberher, which makes sense as McAvoy will be playing the grown-up version of Lieberher's IT character Bill Denbrough. Featured in the same picture is Jack Dylan Grazer who plays the young Eddie Kaspbrak. Grown-up Mike Hanlon actor Isaiah Mustafa also appears, looking like he's ready to begin shooting an intense scene.

After the first movie blew up at the box office to the tune of $700 million worldwide, Warner Bros. is banking on IT: Chapter 2 also scaring up huge numbers. The original movie certainly got a lot of mileage out of standard horror movie techniques, including a lot of jump-scares, but much of its appeal also came from the chemistry between the young actors playing the tight-knit Losers' Club. For the sequel, the young versions of the characters will only be featured in flashbacks, while the main action involves their adult selves. Will audiences respond to Jessica Chastain, Bill Hader, James McAvoy and company as the adult Losers as strongly as they did to the characters' adolescent incarnations? That's one of the big questions facing the sequel.

More: IT Chapter 2: Every Update You Need To Know

Source: James McAvoy/Instagram

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