So much of "Four Brothers" sounds unbelievable on paper, an exercise in preposterous "gritty drama" clichés. Yet the realistic lead performances and John Singleton's level-headed direction make it feel plausible, even likely, that all these events could happen just as they're described. I imagine the studio figured it was getting another dumb, mass-marketable mediocrity and was surprised when the movie actually turned out good.

It is set in November and December in the mean streets of Detroit, where a beloved community fixture named "Mama" Evelyn Mercer (Fionnula Flanagan) was recently killed during a convenience-store robbery. Evelyn, a warm but tough old woman, was foster mother to many underprivileged children of all races over the years, and she legally adopted four who were too incorrigible to attract other long-term parents.

Now these four, all grown and still in various stages of reform, reunite for Mama Evelyn's funeral and, these being the mean streets, to track down her killer themselves. Bobby (Mark Wahlberg), just out of prison, is their leader; Jack (Garrett Hedlund), the baby of the improvised family, follows him faithfully. Jerry (Andre Benjamin), now a responsible businessman, husband and father, wants no part in a revenge plan. And Angel (Tyrese Gibson) is the wild card, more thuggish than the others, and a no-show at the funeral. He has a wild-card girlfriend, too, a fiery Latina named Sofi (Sofia Vergara).

These four tough guys, who joke and wrestle with a vulgar affection for one another that is quintessentially fraternal, know the local hoodlums and have little problem determining that the murder was not an act of theirs. In fact, after watching the convenience store's surveillance tape, Bobby declares, "That wasn't no gang shooting. That was an execution!" (Double negatives aside, one wonders why the store owner still had the tape when surely the police would have taken it.) At any rate, Evelyn appears to have been not an innocent bystander but a target. But who would want to kill dear old Mama Evelyn?

Leads are pursued and plots are thickened and a few goons are dispatched by the merciless Mercer boys in their quest for the truth. They sidestep the police (led by another of Evelyn's former charges, played by Terrence Howard) and they harass local crime bosses. In short, things proceed approximately the way they always do in these films, with the requisite red herrings and false suspects and third-act revelations.

But instead of feeling trite and overdone, the film achieves some of superiority over many of its kind. These actors -- Wahlberg, Gibson, Benjamin and Hedlund -- they take the material seriously, not like throwaway figures in a by-the-numbers revenge thriller, but like real brothers who each deal with crises differently. They are as likely to argue about which game to watch on TV as they are to bicker over plans for avenging their mother's death. Murder plots as elaborate as the one that killed Evelyn don't happen much in real life, but these characters seem real anyway.

Plus, there's that John Singleton magic (which, granted, does not always work, e.g., "2 Fast 2 Furious"). The "Boyz N the Hood" director is famous for knowing the minds and motives of inner-city dwellers, and "Four Brothers" (with a screenplay by David Elliot and Paul Lovett) is alive with the coldness of the streets, the sense that the police have failed them in finding the killers, the grim realization that justice sometimes is not automatic but manual. As Hollywood-ized as the details are, the overall picture feels independent and honest.

THE DVD

VIDEO: The anamorphic widescreen (1.85:1) is preserved. The stark, gritty colors of Detroit in the wintertime are vibrantly transferred to DVD.

For subtitles, you get English or Español.

AUDIO: The sound is presented in Dolby 5.1 Surround, Dolby 2.0 Surround, or French. It's a rich, full soundtrack; the many gunshots really pop.

EXTRAS: Director John Singleton provides a commentary that is more or less a scene-by-scene description of how the movie was filmed, with a lot of anecdotes about how cold it was. He often interrupts himself to say, "Oh, I like this shot" or "Oh, this scene was cool." It's conversational and breezy, if not particularly informative.

Nine deleted scenes are of standard quality: They don't add too much; nothing was lost in cutting them. In one case, with a different version of Evelyn's murder, it was wise to remove it. The one they went with was much more effective.

There are a few mini-features, all 10 minutes or less, all incorporating cast and crew interviews with behind-the-scenes footage:

"The Look of Four Brothers" is about the colors, the sets, the lighting, all that stuff. It's interesting if you're into cinematography and set design.

"Crafting Four Brothers" focuses on the screenwriters' process of creating the story. It offers mostly obvious insights like how they wanted the mom character to seem really motherly.

"Mercer House Shootout" is a pretty interesting look at how the big shootout scene was set up and filmed.

"Behind the Brotherhood" has John Singleton saying, "One of the main themes of the picture is the theme of brotherhood." Really, John? Brotherhood is one of the main themes in the movie "Four Brothers"? Huh. Anyway, it's about casting the actors and making them work together as a family.

The film's theatrical trailer is also included.

IN SUMMARY

"Four Brothers" is a better film than it ought to be. A shopworn premise and a parade of clichés don't hold much promise, yet it works here.

(Note: Most of the "movie review" portion of this article comes from the review I wrote when the movie was released theatrically. I have re-watched the film in the course of reviewing the DVD, however.)