***; M.C. REN; “Shock of the Hour”; <i> Ruthless/Relativity</i>

Now that N.W.A. has shattered into its constituent parts and all four key original members have released albums in the last month or so--kind of like KISS did, but posthumously, and without the clown makeup--the new one from M.C. Ren is the obscurest but by no means the least of them, the “Ace Frehley” of the bunch. “Shock of the Hour” is a small, ugly masterpiece of gangsta rap.

On the densely produced album, Ren hews close to the basic form of the genre laid down on the second N.W.A. album: slow, deliberate beats, pregnant with echo; hard, minimal, minor-key bass lines; and the basic gangsta-rap assertion--don’t slip up, fool, or I’ll shoot you in the head--repeated into infinity. Ren’s deep-voiced, brutal rhyming is as menacing, as portentous of violence, as anything a horror-film director ever set up.

But “Shock of the Hour” also embodies pretty much everything that the mainstream hated about N.W.A.--villainy, vulgarity, over-the-top misogyny--with little of the casual pleasure afforded by, say, Dr. Dre’s “G Thang.” If you weren’t persuaded by N.W.A.’s “Efil4zaggin,” chances are you’d really hate this record.

New albums are rated on a scale of one star (poor), two stars (fair), three stars (good) and four stars (excellent).