After the battle with the Joker (Bill Skarsgård) in 1989, the friends of the Loser League grew up. They once agreed that when darkness comes again, they will gather in Derry again to make a final decision with the Joker. But when the news of the Joker's reappearance came, the friends of the Loser League ushered in an unprecedented inner shock. Some people choose to end their lives, while Billy (James McAvoy), Ricky (Bill Hader), Beverly (Jessica Chastain), Ben (Jay Ryan) and others return to their nightmare hometown at the call of Mike (Isaiah Mustafa) who stayed behind. The increasingly cunning clown attacks the most vulnerable part of everyone's heart, and the nightmare seems to have no end... This film is adapted from Stephen King's original work of the same name.