The story is told through a nonlinear narrative, alternating between two time periods. It chronicles "the Losers' Club", a group of seven outcast children in the fictional town of Derry, Maine, during the late 1950s. The Losers discover they are being haunted by an ancient, trans-dimensional evil that awakens every 27 years to feed on the town's children. After a battle with the creature, they make a blood oath to return to Derry if It ever resurfaces. 27 years later, the killings resume, and the now-adult Losers, who have largely forgotten the traumatic events of their childhood, must return to their hometown to confront the monster one last time.
