American writer-director Trey Edward Shults' lean and mean post-apocalyptic thriller hinges on the interrelated perils of claustrophobia, paranoia and mistrust, honoring that explosive troika despite its limited means. Paul (Paul Edgerton), wife Sarah (Carmen Ejogo), son Travis (Kelvin Harrison Jr.) and their dog Stanley are rural refugees from an unnamed plague that has ravaged the planet. They've just buried Sarah's infected father, who somehow came down with the contagion. The family wears masks outside and stays in at night behind boarded windows and locked doors. Into this fortress stumbles interloper Will (Christopher Abbott), who is immediately gagged and tied. But he claims to be disease free and eventually he and his wife Kim (Riley Keough) and their small child Andrew join the survivors in a communal arrangement.
But suspicion afflicts the house. Teen Travis, fresh into puberty, dreams he's seduced and infected by Kim. Dog Stanley goes missing. A shut door is found portentously open.
Soon, it's all too clear the plague is no less powerful a force than the paranoia that has come to divide the two families. "You haven't been around people when they're desperate," Paul tells Travis as the flashpoint nears. Sure enough, the night brings human monsters born of unquenchable doubt. Shults takes a house and haunts it slowly and at many levels, no mean feat with little more than a script, lighting and killer looks.