There's something of a movie-of-the week earnestness about Kevin Heelan's "Distant Fires," the industrial strength of its expletive-undeleted language notwithstanding. But that quality detracts little from the urgency of its topic and the immediacy of its treatment. Heelan's 1992 drama of racial conflict on the job opened Friday at Actors Theatre of San Francisco in one of the strongest productions the company has ever mounted.

The action takes place on the 10th floor of a highrise construction site on a sweltering summer day in Ocean City, Md. The air is punctuated by the occasional sounds of police sirens and choppers (sound by Michael Smith) from a riot in the nearby black neighborhood of Cambridge, following the police shooting of a young African American (Heelan wrote the play just before the riots in South Central L.A.). The anger of the streets is filtering into and upsetting the delicate racial truce on the job site.

Three of the workers in the 10th floor crew are black, two white, and two are locked in competition for a better-paying union job with the bricklayers on the eighth floor. One of the qualities that distinguishes Heelan's script is the way he weaves his theme of racial conflict into a thicker texture of class divisions and personal differences.

Thomas, in a generally solid, intense portrait by Richard Harder, is an ambitious, hard-working, conscientious African American trying to put as much distance as he can between Cambridge and his efforts to better himself. While waiting to hear whether he got the union job, he's been put in charge of the fractious work crew.

Beauty (Will Hughes), his competition, is a strutting white working-class hero wannabe. Hughs makes him a glorious combination of self-love, explosive inarticulateness and almost paranoid resentment. He's no more bitter, however, about his perception of unified racial antagonism from his black co-workers than he is about the life prospects of the middle-class white kid on the site.

Angel is a white student, played with giggling and appropriately super-serious naivete by Gordon Holmes, who's landed his summer job through family connections.

He's put himself under the protective wing of Raymond (a genial, loquacious Lester C. Jones), an older black worker whose easygoing humor conceals a thoughtful fatalism.

At the opposite extreme is Foos (a smoldering Stuart Elwyn Hall), the angry, hard-drinking, large black man who barely keeps up his end of the job. For him, malingering is a form of rebellion against the white power structure. Foos is the only member of the crew who actually lives in the riot zone. After what he's experienced at the hands of the police the night before, Thomas' work ethic and Raymond's interracial geniality strike Foos as forms of racial betrayal.

Foos makes his case in the play's most powerful scene, a gripping monologue of indignities suffered that seethes with impotent rage. That speech brings the short first act to a strong close brimming with promise that the second act doesn't quite fulfill. But that may be more a fault of director of Bill English's production than of Heelan's script.

English, who also designed the strikingly realistic, cluttered construction site set, has paid less attention to the rhythms of the work place than to the placement of steel reinforcing rods and cement frames. Too often his actors look like they're going through empty motions, rather than executing tasks that have anything to do with the blueprints.Thomas occasionally haphazardly consults.

Rhythm is even more of a problem in the climatic final showdown with the boss (a phlegmatic Michael Desmond). English stages the scene at a snail's pace, apparently to give added weight to Foos's demand that Thomas choose where his loyalties lie. But it doesn't work. The pacing saps the moment of much of its immediacy, and leaves Thomas stranded too long in an unsustainable anguished pose.

It's an attempt to underline a passage that needs no such emphasis. Heelan's "Fires" burn brightly enough on their own.