Everybody has likely attended one of those “duty” dinner parties where, for whatever reason, you just hope to lay low and leave early. That’s the case for Will (Logan Marshall-Green), who attends a get-together at the Los Angeles-hills home of his ex-wife Eden (Tammy Blanchard) and her new man, David (Michiel Huisman). The dozen or so guests include mutual friends of Will and Eden, and it’s established that nobody has seen each other in a while. There are hints of a shared traumatic event. And then there are other unsettling aspects: Cell-phone coverage is nonexistent, drugs are proffered, and somebody starts one of those dreadful “have-I-never” parlor games. The evening seems to hold an agenda, driven by Eden and David’s recent discovery of a new philosophy. Karyn Kusama’s thriller ratchets up the tension quite effectively, dropping clues and establishing relationships as the evening unfolds, and it has something to say about modern social movements in a time of increasingly disconnected communities. I did so want the last reel to be better, but while it works, Kusama’s film is an interesting take on the locked-room freak-out genre.