A film adaptation directed by David Bruckner and starring Rafe Spall and Robert James-Collier was released in cinemas on 13 October 2017.

[4][5] Old university friends Dom, Phil, Luke, and Hutch have decided to reunite on a hiking trip through the Swedish mountains.

However, the shortcut ends up causing the group to become lost and scared, especially after they discover a disembowelled animal corpse hanging from the trees.

Hutch falls through the floor of the church as he and Luke explore it, and find a massive amount of human remains, belonging to adults and children, and animals.

Luke mocks Blood Frenzy as disturbed delinquents until they take him to the attic to see the "ancient ones": centuries-old humans with goats' legs, tended to by the old woman.

While searching for the keys to their truck, Luke hears the old woman singing in Swedish, summoning the creature which she calls "Moder", the word for "Mother".

Upon a rocky plain, Luke descends into a delirium and decides that, despite the many downsides of his life in London, the only thing that matters is being alive.

[9] HorrorNews.net also praised The Ritual, commenting "Nevill's writing style is top-notch and he is one of those guys who can just naturally tell a good story with little to no effort.

"[10] Tor.com commented that "Nevill does a good job exploiting the isolation, dreariness, and enormous age of the Swedish forest setting", but also expressed a desire that the "most intriguing ideas [were] more thoroughly explored".