Trey Edward Shults’ sophomore feature is an apocalyptic thriller that closes with a simple shot of two people staring at one another, an image that carries greater impact than the collapsing buildings and tidal waves that usually end Hollywood end-of-the-world blockbusters. “It Comes at Night” is a small-scaled picture that builds a striking degree of tension through very economical means, a cousin of Eli Roth’s “Cabin Fever” that depends on atmosphere rather than gore for its effect.

The setting is a world in which a plague has struck, leaving the afflicted covered with lesions and threatening others with infection. Ex-teacher Paul (Joel Edgerton) has boarded up his house deep in a forest, where he protects his family. As the film opens, he euthanizes Bud (David Pendelton), his dying father-in-law, and sets the corpse ablaze. That leaves only him, his wife Sarah (Carmen Ejogo) and their teen son Travis (Kelvin Harrison, Jr.) alive—along with their dog Stanley.

Their solitude is broken, however, when Will (Christopher Abbott) tries to break in. Paul subdues him, and after a brutal interrogation to ensure he’s not infected or otherwise dangerous, decides to invite him, along with his wife Kim (Riley Keough) and their young son Andrew (Griffin Robert Faulkner), to join his family in the house and share the work. The six gradually settle into a routine, although there are some bumps in the road: Travis, just coming of age, is obviously fascinated with vibrant Kim, and Will doesn’t seem entirely truthful about his past. There are also episodes that threaten the group: Stanley’s sudden reappearance after running off into the woods, and Andrew’s strange behavior after wandering into Bud’s old room. These will lead to a rupture among the survivors, and that final devastating scene.

Shults’ script is a cunning one, strategically inserting bursts of grim action—like an assault by outsiders on Paul and Will as they drive through the forest—within a string of tense dinner-table conversations and suspenseful treks down darkened hallways, partially illuminated by Travis’ kerosene lantern. There are some genre devices that are disappointingly obvious, like resort to nightmares a character suddenly wakes up from. Overall, however, the script is refreshingly free of cliché.

As is usual in such stories, the characters are not particularly layered, but under Shults’ skilled direction the cast add nuances that bring them to life. Edgerton and Harrison are particularly strong, but Ejogo and Keough add intense maternal notes, and Abbott an underlying strain of unreliability that keeps you guessing. The production is modest, but Karen Murphy’s production design is outstanding, making the house virtually another character, and Drew Daniels’ cinematography is grittily atmospheric. Shults and Matthew Hannam’s editing nicely balances a brooding mood with outbursts of visceral excitement, while Brian McOmber’s pulsating score enhances the sense of menace.

The cleverness of Shults’ film is that what comes at night isn’t mindless violence or splashy makeup but something humanly real—a piercing sense of loss. Some viewers may be disappointed with that, but it seems exactly the right choice in this case, a haunting end to a film about the cost of survival and its aftermath.