Charles Fuller's "A Soldier's Play," is a taut and absorbing whodunit, which is what whodunits are supposed to be. But it is also an uplifting whodunit, and I'm not sure too many other playwrights have managed to pull off that marriage.

A substantial hit for the Negro Ensemble Company in New York, which first staged it two years ago, and the winner, among other honors, of the 1982 Pulitzer Prize, the drama opened a four-week engagement last night at Ford's Theatre as part of its national tour. Ford's hasn't had a stronger attraction in seasons.

The evening's central question is who killed Tech. Sgt. Vernon Waters, as he made his way back to the barracks from the NCO club late one night. But if you consider that the play is set on a military base in Louisiana in 1944, that the victim is a black career man at a time when the Armed Forces were segregated and that racism is never a stone's throw--or a bullet's trajectory away--you will understand that Fuller has more than just suspense on his mind.

Indeed, he is reflecting on the nature of manhood in a society that is still addressing some men as "boys." He is showing how the drive to achieve, to break through the color barrier and to stand on equal footing can boomerang perversely, poison a man's brain and make for his undoing. But Fuller's meditations never impede the forward thrust of his story or defuse the crackle of emotions. What we have, first and foremost, is a complex drama of people--not a pitting of victims against scapegoats.

The play begins with Waters' murder and the obvious rumors that it was the work of the Ku Klux Klan in the nearby town. More for the sake of appearances than out of any deep-seated concern for justice, the Army dispatches a special investigator to "conduct a few question and answer sessions" among the members of Waters' platoon. It is understood that the inquest will have the lowest of priorities. But the headstrong investigator, Capt. Richard Davenport, turns out to be a black and he is not about to close the case so summarily, even though it means bucking the white military establishment.

In the course of the "question and answer sessions" that follow, Fuller employs flashbacks to fill us in on the various incidents preceding the murder and to flesh out the curiously provocative character of Waters himself. A fierce disciplinarian, Waters sees himself as a soldier "first, last and always," and boasts that he is "the kinda colored man who don't like lazy, shiftless Negroes" because they confirm the old, nasty stereotypes. Under the martinet is a zealot who has resolved to burn those stereotypes out of the race. If he has to destroy some of his own men in the process, so be it.

As in all adroit mysteries, the facts of the case come out tangentially, each new revelation thickening the story and adding a layer of ambiguity. While Fuller has surprises to spring, they are astutely planted along the way. Even the scenes of comic roughhouse in the barracks are not quite as innocent as they appear. The careful structure of "A Soldier's Play" is sometimes referred to as "well-made dramaturgy," a term that has fallen into dispargement lately, although that still takes nothing away from Fuller's craftsmanship.

The Negro Ensemble Company's last visit to town, the guest engagement of "Home" at Arena Stage, was marred by some second-rate casting. There are occasional weak links in "A Soldier's Play," too, but they are not enough to rob the play of its force. Raspy-voiced Graham Brown brings blunt power to the role of Waters, a rampaging bull in the barracks. The performance has a certain intentional awkwardness, as if Waters could veer out of control at any moment. Only in his scenes of drunkenness does the actor himself lose control.

Similarly, Charles Brown's performance as Davenport strikes me as most effective when the actor is sticking to the subdued tones of irony and introspection. His periodic run-ins with the white captain on the base (David Davies) tend to escalate into shouting matches.

But the soldiers under the grill--Steven A. Jones, John Dewey-Carter, O.L. Duke and Samuel L. Jackson--are all sharply delineated and skillfully contrasted. Two of them are even better than that. As an outspoken private, who stands up to Waters, Eugene Lee manages to hide his cards until the end, at the same time he is actually showing us his hand every step of the way. And Ben E. Epps gives a strappingly muscular portrayal of the good-natured, guitar-strumming recruit who inadvertantly provokes Waters' lethal wrath.

Douglas Turner Ward has directed them all with economy and his juxtapositions of past and present are deftly conceived. The spare abstract set by Felix E. Cochren looks a little too spare on Ford's lofty stage, but Allan Lee Hughes' evocative lighting relieves some of the olive-drabness.

Although "A Solider's Play" is far removed from the much of the angry black theater of the 1960s and '70s, that postulated the unity of the black race, casting off its shackles, Fuller does make the point in "A Soldier's Play" that a long overdue struggle for equality is under way. Fuller, however, is not a proselytizer; he is a dramatist dealing with weakness and strength, courage and cowardice. As a result, you will find that struggle to be as uplifting as it is inexorable.

A SOLDIER'S PLAY. By Charles Fuller. Directed by Douglas Turner Ward. Sets, Felix E. Cochren; costumes, Judy Dearing; lighting, Allen Lee Hughes. With Graham Brown, David Davies, O.L. Duke, Eugene Lee, Samuel L. Jackson, Steven A. Jones, John Dewey-Carter, Ben E. Epps, Charles Brown. At Ford's Theatre through Nov. 20.