“Blue ruin” is an archaic synonym for “catastrophe.” “Blue Ruin,” a compact yet complex thriller from writer/director Jeremy Saulnier, is anything but. It hits the bull’s-eye for taut suspense, sharp characterization, stylish direction and quirky, confident storytelling. It won the International Federation of Film Critics Award at Cannes last year and I recommend it enthusiastically to all but the blood-squeamish. Even they should watch it through finger-slits. There’s a care and precision to its craftsmanship that will earn it a spot on many “Best of 2014” lists.

The central figure, Dwight, became a homeless drifter after the 1990s murders of his parents. The alleged killer is about to be released. Dwight, a gentle man-child, determines to kill him, though he has no assets, no combat skills and no plan. By making its lead character an underdog in way over his head, “Blue Ruin” ruptures the revenge formula. Dwight’s quest becomes a dark, Coen-esque comedy of errors. His efforts to acquire a gun are a study in low-key wit.

The story structure is novel. Just 18 minutes in, Dwight achieves his objective. That’s just the beginning. The rest of the film details the spiraling consequences. Rather than settling the score, Dwight has set off a new round of reprisals, exposing his sister and her family to attack from the dead man’s sociopathic, well-armed clan.

In scene after scene, Dwight gets himself believably into a corner where he could be discovered or killed, and the film makes us sweat it out with him. As his options dwindle and the violence escalates, we find ourselves pulling for him. His worst decisions seem feasible under the circumstances. Yet the film, with welcome moral complexity, never insists that we root for him. Its world is an untidy place where everybody feels they have just cause. Bit by bit we learn about connections between the two families that color the blood feud, a complicated weave of information that never feels like exposition dumping.

Dwight’s opponents are a rotten bunch, yet they have surprising dimensions. One of the worst antagonists has the film’s best smartass lines; Saulnier takes enough time developing his role that we don’t want to see him eliminated.

The violence, when it occurs, is purposefully uncomfortable. There’s fallout from every injury. At one point Dwight tries to remove a crossbow shaft from his leg with self-surgery, a sequence that will have you eating your fist and whimpering. In this film, wounds hurt. Luckily Saulnier drops pauses into this 90-minute thrill ride so we can catch our breath.

It’s impossible to imagine how another actor could have made a better Dwight than the endlessly watchable Macon Blair. He resembles a younger Paul Giamatti and possesses the same hangdog charisma. By showing us that Dwight’s scared out of his wits, he keeps us on the amateur killer’s side even as his plan inevitably goes sour. His performance is one of the greatest strengths of this modest-but-flawless gem.