Ah, lazy, hazy summer — that time when Americans escape to the countryside and get killed. “The Strangers,” from first-time director Bryan Bertino, yields an early, serviceable chunk of home-invasion horror with echoes of “Them,” “Funny Games,” and “Vacancy.”

Kristen (Liv Tyler) and James (Scott Speedman) are a couple in formal wear who crash at his family’s empty country house after a friend’s wedding reception. Their particular brand of relationship limbo casts a spell of melancholy and vulnerability over the deft introduction, accessorized with rustic vinyl (Joanna Newsom, but brusquely succeeded by Merle Haggard).

But any troubles they may be having with each other pale in comparison to the trouble that’s to come. Before long, this horror tale gets down to business with a 4 a.m. knock on the door and some immediate carnage, courtesy of two women and a man who break into the house sporting apple-dimpled masks and a feed bag. Lacunas of suspense are allowed for the usual victim-oppressor chitchat: observation (“That was weird”), brainstorming (“Should we go outside?”), and late-in-the-game demurrals (“You don’t have to do this”). Frights come mainly from jumps, not gore; the tormentors find an accomplice in an editor on the film who gives them time to scram between cuts.

All of this may sound ordinary, but “The Strangers” is bearable, if not excellent, precisely because it doesn’t strain for sadism or self-consciousness. Mr. Bertino drops a mild twist here and there (the biggest bloodbath comes from an unusual source), but he lends the closest attention to the frame of his simple composition: In the bleary daytime flash-forward of the movie’s opening, two child proselytizers (again with the formal wear) chance upon the crime scene.

An able tenser of neck tendons, Ms. Tyler does not embarrass herself (politely given the opportunity to change from nightgown into jeans before the assault). Mr. Bertino avails himself of several close-ups of the actress’s arresting face, and if everyone at some level is marking time with this one, watching the film is a sight better than, well, being terrorized by a pack of spooky kids on a summer’s night.