Not a horror movie, at least in the usual sense, but a disappointing feature by writer-director Preston A. Whitmore II about four black marines dropped into a combat zone in Vietnam in 1972. Even if one accepts the absence of Vietnamese in the storya standard omission in Hollywood movies about Vietnam, ratified by Forrest Gump and sadly indicative of a continuing blind spot in this country’s post-60s imaginationthe flashbacks to what the four marines did back in the States are especially perfunctory and feeble. And after a promising early stretch that offers some lively, raunchy dialogue, the movie quickly settles down to formulaic speeches and music-video pacing. With Joe Morton, Eddie Griffin, Allen Payne, Vonte Sweet, and Roger Floyd. (JR)