Will (Logan Marshall-Green) attends a party at his ex-wife’s new home — and soon suspects that something’s amiss — in “The Invitation.” (Drafthouse Films)

“Yeah, they’re a little weird. But this is L.A.”

That’s the reassuring — and entirely wrong — rationalization offered to Will (Logan Marshall-Green), the most anxious guest at the dinner party that serves as the principal setting of “The Invitation.” The location, a remote hillside house, belongs to Will’s ex-wife, Eden (Tammy Blanchard), and her new husband (Michiel Huisman). They’ve joined a cult that just happens to be called the Invitation, and they want to introduce their circle of diverse, upscale friends to its “peace.”

Will and Eden split after a shared trauma, so the others assume that those bad memories explain why he’s so uptight. But Will suspects that there’s something more ominous about the reunion, which is given an even creepier tenor by the presence of two other cult members: an older man with a menacing demeanor (John Carroll Lynch) and a young woman whose flirtatiousness borders on the pathological (Lindsay Burdge). Director Karyn Kusama — who’s never topped her 2000 debut, “Girlfight” — amplifies the sense of dread with tightly framed, shadow-draped compositions.

All this foreboding produces no suspense: It’s evident from the bloody prologue where “The Invitation” is headed. The filmmakers keep trying to make Will appear paranoid, but he’s not fooled for long — and most viewers won’t be, either. They’re more likely to be irked as this overlong un-thriller delays the inevitable carnage. Even the final shot, which is meant to shock, is as predictable as the release of yet another sequel to “The Purge.”

Unrated.  At area theaters. Contains violence, nudity, sexual situations and obscenity. 100 minutes.