"Brothers," now at the Town Lincoln and Hillside Drive-in theaters, is a stark, sometimes moving exploration of racism in contemporary American prison life. It also stumbles along, however, at times when the documentary effect overrides the movie's dramatic features.

The sharply delineated film is based on one of the most dramatic political and social episodes of the last decade: the saga of Soledad Brother George Jackson, whose imprisonment and writings stirred the interest of millions about prison conditions for blacks.

Political activit Angela Davis took up his cause and at the same time became romantically involved with him. The relationship resulted in a courtroom shootout that took the lives of two prisoners, Jackson's younger brother and a judge. Jackson was shot by a prison guard in 1971.

Edward and Mildred Lewis, the husband-wife team that wrote and produced the film, contend that it's not based on George Jackson's story but that it is taken from the experiences of several black political prisoners' including the Rev. Ben Chavis, of the Wilmington 10. That may be true of the film's general purpose, but no of its specific storyline.

The film, starring Bernie Casey as a prisoner named David Thomas, the rivets on one man's political self-education and the awareness he generates among fellow inmates about their situations. Thomas comes alive after reading Malcolm X, Maxim Gorky and Frantz Fanon.

He turns from a sullen loner to someone black inmates rally around in their fight against white racist guards and prisoners. Thomas, sensitively played by Casey in low-key fashion, starts an underground newsletter to alert outsiders to harsh prison conditions. He also publishes a book.

Like George Jackson, he is imprisoned after an apparently harmless role in a gas station holdup. Also in the manner of Jackson, his cause is taken up by a black female philosophy professor-political radical - in this case her name is Paula Jones, strongly portrayed by Vonetta McGee.

She stirs up national interest in his plight. His younger brother dies in a shootout outside a courthouse. Thomas is fatally wounded in a prison guard setup while trying to protect the lives of fellow inmates. And all these events occur in California.

The resemblances to real life speak for themselves.

Despite the skillful use of real life events, the Lewises have failed to add sufficent fresh dramatic qualities that would enrich what we already know - or expect - about a case like Davis'.

The harshness of prison life is clearly depicted, partly because the film was shot at the North Dakota State Prison, using inmates in feature roles and as extras. But the underlying emotional shackles or torment of incarceration is only hinted at briefly.

Instead of exploring several aspects of Thomas' personality and the complex responses and feelings of those around him, the film dwells too much on events. It relies on the power of sequential incidents to give it force, not the strength of individual response and interaction. Indeed, it probably conveys a raw energy to those who have memories of the George Jackson story. But it may have less dramatic strength for people unaware of Jackson.

What's more, the movie's theme, racism, is relatively easy to write about superficially. Its circumstances - and symbols - are familiar to most of us. They only need to be maneuvered. But it's harder to show the complicated relationship between people and events without relying too heavily on banal formulas.