"A Flash of Green" is an unsettling movie about getting by in a malevolent world -- a film noir in living color by writer-director Victor Nunez. Like his much-praised first feature, "Gal Young Un," the story is set in his home state of Florida, and despite a slow pace and quiet tone, it has a cumulative narrative power.

The movie is based on the 1962 novel by mystery writer John D. MacDonald -- a tale of corruption under the fronds in the beach town of Palm City. The evil here is baked by the sun. Its colors are washed and dried. This is, in some ways, the daytime version of "Body Heat."

An oddly grinning Ed Harris stars as Jimmy Wing, a small-town newspaper reporter who plays both sides of a blood feud between land developers, who want to build a big resort, and conservationists, who want to stop it. Wing's treachery is such that at the very moment he is romancing his best friend's widow Kat Hubble (Blair Brown), a "Save Our Bay" activist, he is working to dig up dirt on her conservationist friends at the behest of power-mad county commissioner Elmo Bliss (Richard Jordan, whose voice is a blissful tremolo).

Bliss' tactics begin with petty blackmail and escalate to horse-whipping. But while Bliss is motivated by ambition -- he wants to be governor and the resort will help -- Wing's villainy is mean and senseless, born of despair. "I needed something to do," he confesses, like an existential antihero, sick to death of the world but compelled to stay in it.

He tries to redeem himself in the end. It's an open question whether he succeeds.

Harris, looking as though something has sprung loose behind his baby blues, gives a deftly out-of-kilter performance -- one that might explode at any second and occasionally does. Whether betraying friends, exposing misdeeds (his own, via a front-page exclusive), or taking brutal beatings from Elmo's thugs, Wing seems possessed by a kind of brain fever. (His wife, briefly seen, dies in a mental hospital). "I'm a reluctant participant," he says at one point.

Blair Brown plays the widow with a quiet, desperate strength -- and still manages to look uncannily like Jackie Onassis, as she did in "Kennedy," a TV mini-series of a few years back. The fine ensemble also includes William Mooney as a sneering businessman, Jean De Baer as a defiant conservationist, Joan Goodfellow as a hard-bitten floozy and George Coe as a softhearted reporter -- in contrast to Wing's practiced professional callousness.

Nunez, who also worked the camera with an eye for faded beauty, has made Palm City a self-contained world where there can be no appeal to a higher authority. While sometimes he's a bit heavy on the symbolism -- having Wing, at one point, fiddle with a two-faced doll -- he usually handles the material with admirable subtlety, letting the story all but tell itself.

As for the "flash of green," it is Wing's old Aunt Middie's expression for a rare light phenomenon of Florida sunsets -- a moment for making wishes, when they might even come true. Aunt Middie sees the flashes regularly. Jimmy Wing never does.

A Flash of Green, now playing at the K-B Foundry 7 and K-B Studio, is unrated but contains violence and sexual situations.