Putting a festive twist on what at first appears to be a series of Manson family-style slayings before evolving into something more like a home invasion thriller, Jenn Wexler’s second feature is set during Christmas 1971 at the slightly ominously named Blackvale Catholic girls’ boarding school. A couple of misfit students, Samantha (Madison Baines) and Clara (Georgia Acken), remain at the school over the winter break, supervised by their teacher Rose (Chloë Levine) and her boyfriend Jimmy (Olympic medallist turned actor Gus Kenworthy). Neither of the girls are happy about having to stay there kicking their heels, but as events unfold it transpires that boredom will be the least of their worries.

There’s an art to keeping an audience guessing, although different genres have different rules which it is unwise to completely ignore. Wexler’s script, co-written with Sean Redlitz, understands the need to balance storytelling surprises with an overall story-world coherence. You’re never left in any doubt that The Sacrifice Game is made by film-makers with affection and respect for horror movies – but it might not be the type of horror movie you thought it was at first sight.

Exceptionally cast, well-judged performances help sustain these tonal shifts. Brimming with Christian-Slater-in-Heathers energy, Mena Massoud is a menacing OTT treat as the cult’s alpha dog, seemingly having a lot more fun here than he did as the hero in Disney’s Aladdin. Laurent Pitre is a low-key delight as Doug, the closest thing the gang has to a nice guy, occupying the social niche in the group that Jim/Tim from The Office would fill if he got a job in a murderous cult instead of a paper sales company. Last but definitely not least, Acken recalls the early work of Christina Ricci as a quiet loner with a presence of mind that belies her apparent social status and age. She deserves to go far.

• The Sacrifice Game is available from 8 December on Shudder.