The backwoods-gothic terrain may be familiar, but the jolts are doled out with an expert hand in “Blue Ruin,” a lean and suspenseful genre piece that follows a bloody trail of vengeance to its cruel, absurd and logical conclusion. Writer-director Jeremy Saulnier shows impressive progress from his funny-scary 2007 debut, “Murder Party,” with this tense, stripped-down tale of a Virginia drifter who finds himself in way over his head when he tries to exact payback for his parents’ deaths.

Saulnier cleverly establishes a man-on-the-run theme in his opening shot, before the action proper has even started. Thereafter the camera practically stays glued to Dwight Evans (Macon Blair), a quiet vagrant who gets by sifting through Dumpsters and sleeping in his beat-up blue Pontiac. Yet his seemingly pointless existence is marked by curious flashes of daring and resourcefulness, if not exactly great intelligence, and he suddenly snaps into action and returns to his rural Virginia hometown upon learning that one Will Cleland has been released from prison.

Making it clear there’s a score to settle without immediately disclosing the gruesome details, the script lures the viewer into an unnerving sense of complicity as Dwight follows Will and his folks to a bar and, armed with a small knife, initiates the first of several brutal setpieces. The filmmaking is clean and efficient but the killing isn’t, and in the course of his clumsy, foolhardy getaway, Dwight ends up putting Will’s entire gun-toting redneck family on his tail. In a twist that streamlines the narrative considerably, the Clelands opt not to inform the police of the attack, choosing instead to keep things “in-house.”

While Dwight’s not-so-bright actions generate some darkly humorous beats (none grislier than when he tries, and fails, to clean a nasty arrow wound), Saulnier resists turning his protagonist into an object of outright ridicule, never compromising the audience’s intense identification with this reluctant renegade. In name and appearance, Dwight is the sort of pudgy, clean-shaven Everyman more suited to an office cubicle than a shootout, and even as the arguable aggressor in this scenario, he seems to act more out of fear and protectiveness than out of a real desire for retribution.

Blair’s engaging, soulful-eyed performance succeeds by locating the sweet spot between idiot and amateur, predator and prey. Repeatedly, Dwight plans ahead, takes calculated risks and still messes up, and much of the film’s tension derives from his very fallibility, as well as his increasing awareness that none of this can possibly end well. If the climax goes inevitably over-the-top, it’s nonetheless the sort of gruesome finish the story’s steady, merciless buildup demands.

Carefully exploiting the audience’s fear of what it can’t (or can only partially) see, Saulnier’s shallow-focus widescreen compositions amp up the suspense at key intervals, as do Julia Bloch’s crisp editing, Matt Snedecor and Dan Flosdorf’s meticulously layered sound design, and Brooke and Will Blair’s ominous synth score. While Dwight is often the camera’s sole focus, warm character notes are provided by Amy Hargreaves as Dwight’s sister, who is at once grateful for and angered by his reckless actions, and Devin Ratray as an old high-school friend whom Dwight enlists to help, in one of his smarter decisions.