Other Mommy — R (A-lll)

Jay Duplass, Arabella Olivia Clark, and Jessica Chastain star in a scene from the movie “Other Mommy.” The OSV News classification is A-III — adults. The Motion Picture Association rating is R — restricted. Under 17 requires accompanying parent or adult guardian. OSV News photo/Bernard Walsh, Universal Pictures A number of scenes in the passable chiller “Other Mommy” (Universal) feature a secluded seaside mansion, a lighthouse and some cliffs. As such traditional visuals suggest, the film is mostly an old-fashioned frightfest, though it does include a single, very bloody sequence as well as vocabulary that marks it as strictly for grown-ups.

The figure of the title is a shape-shifting demon who, among other guises, frequently impersonates Ursula (Jessica Chastain), the mom of seven-year-old Bella (Arabella Olivia Clark). Since the fiend has the ability to ingratiate herself with Bella, the child is initially more or less comfortable in her company.

But the malignant visitor has a goal: it wants Bella’s permission to inhabit her body, at least temporarily. Since Bella persists in denying this wish, the ghoul gradually becomes more desperate and destructive, eventually terrorizing Bella, Ursula and Bella’s well-meaning but ineffectual dad, Russ (Jay Duplass).

Bella’s parents, being thoroughly secular, have no idea how to react to the manifestations of the diabolical they’re experiencing. So they reluctantly turn to Ursula’s estranged mother Ruth (Karen Allen), an eccentric dabbler in the occult. But this move backfires badly.

In adapting Josh Malerman’s 2024 novel “Incidents Around the House,” director Rob Savage mostly steers clear of bloodletting and concentrates on disorienting dread.

Nathan Elston’s script eventually serves up some third-act explanations for the unfolding crisis, connecting it to family secrets of a less-than-startling nature. But this link seems to rely on rather murky psychology and fails to satisfy. Despite this flaw, “Other Mommy” is, overall, an adequate — albeit unremarkable — thriller.

The film contains horror violence with brief but intense gore, gruesome sights, an adultery theme, fleeting drug references, a few instances each of profanity and milder swearing, numerous rough terms and a couple of crude expressions. The OSV News classification is A-III — adults. The Motion Picture Association rating is R — restricted. Under 17 requires accompanying parent or adult guardian.