Steve James returns to the South Chicago terrain he essayed to such strong effect in “Hoop Dreams” in this new documentary, and though the result isn’t as shattering this time around, it’s not because the subject is less powerful—indeed, it’s more so. Rather it’s because “The Interrupters” is a more conventional work on a broader canvas.

In a very real sense the film represents a counterpart to “Dreams.” While that film followed two young men trying to work their way out of their desperate circumstances through their talent at basketball, this one portrays the dangerous, even murderous situation in which all the young people of the area find themselves and the efforts of a group of their elders to stop, or at least lessen, the cycle of violence. The documentary is set against news reports about the epidemic of killing that’s blighted the South Side, especially in terms of the deaths of children. (It cites, though almost in throwaway fashion, the death of Derrion Albert, a youngster killed in a melee outside a school whose case brought national attention to the situation.) And it focuses on a dedicated bunch of activists called the Violence Interrupters—mostly men whose own past actions landed them in jail, but also academic and religious leaders and women who suffered neglect and abuse as children—who literally interpose themselves in situations where retaliatory violence threatens and try to prevent it.

Those who emerge as the centers of attention are associated with a movement called CeaseFire, founded by scientist Gary Slutkin, who looks on a culture of violence in the same way as he would an infectious disease whose spread can be halted by timely intervention. James hones in on three of its members who literally put themselves into what could become the line of fire to short-circuit revenge assaults and cool down arguments that could escalate into killing. Ameena Matthews is the daughter of a gang leader who’s become an outspoken advocate of peaceful solution to problems and a mentor to young women as troubled as she was. And Ricardo “Cobe” Williams and Eddie Bocanegra are men with checkered pasts themselves—the former an ex-con and the latter a man still haunted by a murder he committed years before. We hear testimony from all three about their own histories and the lessons they’ve taken from them, watch them discuss strategy in groups presided over by CeaseFire director Tio Hardiman, and see them trying to make a difference by intervening when violence threatens—and in some instances is on the very verge of erupting.

“The Interrupters” is at its most powerful in the fly-on-the-wall sequences of the protagonists on the streets, defusing dangerous situations. But it personalizes matters poignantly in the ongoing story of Caprysha, a teen whom Ameena tries to advise with only limited success. And a scene in which a young man approaches the victims of the crime for which he’s served time to express regret and ask forgiveness has real emotional punch.

James’ film isn’t revelatory in terms of presenting a world we didn’t already know existed. But it gives that world tactile force and humanizes it in a fashion that brief, detached news reports can’t. And, of course, though it’s about one specific city, it offers lessons about the desperation of the young and the need for community involvement that are applicable all over the country. Though formally conventional, it carries a powerful message about the reality of life in the inner city and the struggles of those who live there to break the cycle of violence.