Imagine the awkwardness of attending a dinner party thrown by an ex-spouse in the lavish home you both once shared. Throw in the unhealed wounds of a child’s tragic death, the aftermath of which destroyed your marriage. Now picture friends you haven’t seen in forever, bars on the windows, a locked front door and a recruitment video for some kind of cult.

Such is the scenario faced by Will (Logan Marshall-Green, looking a lot like a bearded Tom Hardy). On the drive up to a reunion dinner in the Hollywood Hills, Will and his new girlfriend, Kira (Emayatzy Corinealdi) hit a coyote. Will is forced to bludgeon the suffering animal with a tire iron, an act that bears some parallel to the blunt force accidental death of his son a few years prior. Neither Will nor his ex-wife, Eden (Tammy Blanchard), has handled the death well. Throughout the film, we’re given flashback sequences of the painful aftermath, including Will forcibly preventing Eden from killing herself. In fact, Will hasn’t even seen Eden in two years—she had left the country and lived in a mysterious Mexican locale. Now that she’s back, Eden’s all-consuming grief is a thing of the past. She claims that she’s learned to shed all that useless pain, and now she sports an unsettling perma-smile.

The title of The Invitation applies both to the dinner party and to the name of the strange new religion that Eden and her partner, David (Michiel Huisman), now follow with unblinking devotion. Early on, this thriller plays with our sense of reality, as Will begins to perceive impending peril. Seen through his eyes, we never quite know whether the ominous vibe in his onetime home is his own grief-stricken paranoia or the presence of an actual threat. His friends seem to defer to their hosts. Eden and David insist that the new bars on the windows and locked front door are necessary due to a recent spate of break-ins in the area. Will begins to suspect that another friend who is running late and not answering his phone may be missing for more nefarious reasons. A hyper-sexual stranger in their midst (Lindsay Burdge) sets him on edge, as does the presence of an oddly menacing enforcer figure (John Caroll Lynch), both of whom were involved with the transformative cult experience in Mexico.

What makes The Invitation succeed as a thriller is the inherent tension of ex-spouses once again occupying the same space in a social setting. Besides, there’s typically an undercurrent of awkwardness in dinner parties among friends who have outgrown each other. Director Karyn Kusama turns up the heat on this tension and mixes in harbingers of doom that may only be in Will’s mind. Either way, it’s clearly going to boil over into chaos. Even after David and Eden show a disturbing cult recruitment video and then begin a party game that bends the mores of monogamy and good taste (prompting a more modest party guest to leave—or does she?), most of the attendees initially seem to find Will’s skittish behavior the most off-putting experience of the night. The Invitation errs somewhat in making many of the party guests far too obtuse, but then again the truth turns out to be stranger than any fashionable L.A. socialite would expect.

Debuting at SXSW almost a year ago, The Invitation now echoes 10 Cloverfield Lane as a film whose tension is built in a claustrophobic environment in which the sinister threat may or may not be real. This film plays with that paranoia in a way that rewards the viewer for enduring the vapidity of the vintage wine-swilling party guests. Despite some believability issues, and the slightness of the film as a whole, it’s difficult to resist the The Invitation’s Kool-Aid.