In the small American town of Derry, a young boy named Georgie Denbrough (Jackson Robert Scott) is dragged into a storm drain by a mysterious creature that introduces itself as “Pennywise the Dancing Clown”. His disappearance reveals a long, horrifying history of similar disappearances and mass tragedies in Derry, and leads his older brother Bill (Jaeden Lieberher) and his friends to begin investigating the cause and Pennywise’s true nature.

It is a film adaptation of the popular horror novel by Stephen King. Or, more accurately, it is an adaptation of that novel’s first half. In a relatively bold move – albeit one that seems to have already paid off – New Line Cinema split King’s lengthy novel into two halves. They have filmed and released the first, and thanks to its enormous commercial success they have already pencilled in the sequel for September 2019.

It is broadly a very successful translation of the book to the screen. Certainly it offers more than its fair share of well-developed horror sequences, each invoking various senses of shock, surprise, fear and dread. It is also very well cast and written, with a strong ensemble of juvenile leads and a brilliantly unsettling Bill Skarsgård as the iconic Pennywise.

An awful lot of liberties have been taken with King’s novel, some of them obvious – King’s notorious orgy scene mercifully does not occur – and some rather perplexing. The story has been shifted from 1958 to 1989, with is a change that makes sense: King’s novel split the action between the 1950s and the 1980s (then the present), so bringing the first half forwards in time enables 2019’s sequel to be essentially set in the present day.

In one specific case a change feels borderline offensive: Mike Hanlon (Chosen Jacobs), an African-American kid and member of the self-proclaimed “Loser’s Club”, spent the novel as a de facto custodian of Derry’s history. In the film that role has been passed over to the white Ben Hanscom (Jeremy Ray Taylor). One can imagine a creative decision taken somewhere to transfer Mike’s function to beef up Ben’s – possibly under the thinking that the racism expressed against Mike by town bully Henry Bowers (Nicholas Hamilton) was character development enough – but it is a tone-deaf decision and simply comes across as somewhat racist in effect. It does not ruin the film, but for viewers aware of the original novel it does dent it somewhat.

The film’s scares are top notch, as is the acting and direction. The pacing feels slightly off; too much happens too soon in the film’s opening act to really settle the audience into the story, and that leads to a weird sense of catching up during the first half hour. The greatest victim of the fast pace is Skarsgård, who gets plenty of opportunity to jump and run about in scary ways but never really gets enough time to further showcase his character’s personality. He is already working under something of a shadow – Tim Curry’s performance in the role in a 1990 miniseries will easily be considered definitive by many – and while he cuts an enormously impressive figure it does feel like he has been a little short-changed.

It is imperfect, but given the weight of expectations upon it by fans of both the novel and the miniseries it has done an absolutely outstanding job. It’s a smart, wildly effective ghost train of a movie, and does its most important job – being a scary horror movie – with style and enormous skill. Movie adaptations of Stephen King run the gamut from all-time classics to career embarrassments; It is one of the really good ones.