Jessica Chastain has reported for duty on IT 2. The Oscar-nominated actress is taking on the role of Beverly Marsh in the horror sequel, filling in for Sophia Lillis, who played the role in the first movie last year. Lillis will return via flashbacks in the sequel, but it's Chastain who will be doing the heavy lifting, as this installment takes place 27 years after the events depicted in IT. Now, Chastain has revealed that she's begun filming via an Instagram post that shows her side-by-side with her younger on-screen self.

The image posted to Jessica Chastain's Instagram is half young Beverly, half adult Beverly, with their faces morphing together. It illustrates just how perfect this casting is and why she was such a popular choice for the role so early on. It doesn't hurt matters that Chastain previously worked with director Andy Muschietti on his debut feature Mama, which helped open the door for this fan casting to become a reality. Filming is now underway on what could easily be the second most anticipated sequel of 2019, trailing only Avengers 4.

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IT: Chapter 2 will also feature James McAvoy as Bill Denbrough, Bill Hader as Richie Tozier, James Ransone as Eddie Kaspbrak, Isaiah Mustafa as Mike Hanlon and Jay Ryan as Ben Hanscom, rounding out the adult version of The Losers Club. Xavier Dolan was recently added as Adrian Mellon, with Will Beinbrink brought on board to portray Tom Rogan, both characters from Stephen King's book that help assert that this will be a very faithful adaptation of the material. Teach Grant was recently tapped to play the adult version of bully Henry Bowers, with Jess Weixler set to play Bill's wife. Last, but certainly not least, Bill Skarsgard is back as Pennywise the Clown.

Andy Muschietti directed IT to great success and having him back for the sequel is a credit to the project. Writer Gary Dauberman also came back to handle scripting duties. The first movie passed through several hands on its way to production, as it had been in development at the studio for quite some time, but Dauberman tackled the follow-up on his own, surely with input from Muschietti. IT 2 will tackle the second half of Stephen King's novel that sees the Losers return to Derry, Maine to finish what they started nearly three decades earlier.

The production of IT was pretty secretive, with only a handful of photos making it online during the course of filming. It's quite possible that the studio will want to keep an even tighter lid on things this time around, given the success of the first movie. So even though filming is underway, don't expect a tidal wave of revealing set photos to start pouring in. But horror fans are surely happy to know that the sequel is officially on its way to becoming a reality. IT: Chapter 2 arrives in theaters on September 6, 2019. You can check out Jessica Chastain's Instagram post for yourself below.