DIRECTOR JOHN Singleton's avowed love of John Wayne movies is readily apparent in "Four Brothers," a western without cowboy hats. Set in Detroit, where the hombres, bad and good, ride through town on steeds of steel instead of palominos, the movie -- whose plot concerns the search by four once-troubled adopted brothers (Mark Wahlberg, OutKast's Andre Benjamin, Tyrese Gibson and Garrett Hedlund) for the guys who killed the saintly woman who raised them (Fionnula Flanagan) -- isn't just any old western, but a revenge western.

As such, it doesn't have room for such things as nuance of character or moral complexity. The good guys are the good guys, even if they're not above breaking the law (and a few bones) themselves in the pursuit of payback. And the bad guys are, well, very, very bad, even if some of them, in the end, demonstrate a change of heart. If the movie doesn't have room for doubt of any kind, that's because it is, at heart, small. It does what it does, which is to satisfy a need to see vengeance exacted (and of a rather base variety), and then it gets out.

Quick? Not especially. Not at close to two hours. Clean? Hardly, with the high body count in the wake of the boys' destruction. But small nonetheless.

I mentioned that "Four Brothers" was set in Detroit, but it's really a fantasia of that city, in the way that westerns are fantasias of the West. It's a Detroit where everyone plays hockey, black and white; where the cops are incompetent, corrupt, doomed or nonexistent (especially during one protracted, bullet-strewn chase scene through deserted, snow-covered streets); and where the iced-over lake is merely photogenic set dressing for the climactic showdown between the mobster villain (Chiwetel Ejiofor) and the main hero (Wahlberg, whose deeply furrowed brow is starting to look like Ice Cube's).

My biggest problem with "Four Brothers" is not what it is. As a revenge fantasy, it's fairly satisfying, and the twists have just enough torque to maintain interest. My problem is more with how it accomplishes its goals than with what they are.

That's because, for all its well-drawn lines between good and evil, "Four Brothers" is ultimately passive entertainment. As storytelling, the script by David Elliot and Paul Lovett doesn't ask the audience to participate -- to share the protagonists' emotions, such as grief -- so much as it insists that we sit back and enjoy the bloody ride.

To the extent that we know the main characters at all, we know them as types: barely reformed, hot-tempered thug Bobby (Wahlberg); ladies man Angel (Gibson); straight-arrow, married businessman Jeremiah (Benjamin); and wussy aspiring rock star Jack (Hedlund).

As we follow them in their search -- not so much for justice as for brutal retribution -- what's most disturbing is how we're made not to care. About anything. Not to care whether they've got the right perps or whether the perps even deserve the summary execution they're handed. I wasn't just troubled by the fact that several members of the audience laughed whenever someone got shot in the head but that the movie seemed to actively encourage such a reaction.

If "Four Brothers" spent half as much energy making us feel something for its heroes as it spent making us feel nothing for their victims, it would be a far better, and far more engaging, film.

FOUR BROTHERS (R, 108 minutes) -- Contains obscenity, sexual content and violence. Area theaters.

"Four Brothers": Mark Wahlberg, left, Tyrese Gibson, Andre Benjamin and Garrett Hedlund.