Down? You bet. Dirty? Absolutely. But also sick, sick, sick. When Robert Ludlum (below) has a paranoid fantasy, it's at least idiotically exuberant; King's, however, is smeared with feces, blood, and drool. In pseudo-hard-boiled short sentences, N.Y. cop John Mekkler tells us how he gets thrown off the force for being ""a goddamn faggot."" How he goes for solace to his old teacher-lover and finds him hanging from the ceiling. How he drowns his anger (""Fag ex-cop plans vengeance"") in pick-up sex. How he goes to a psychiatrist but discovers the shrink (soon dead) is part of the same conspiracy that killed the teacher. So is his pick-up lover. So is a painter whom Mekkler sort of accidentally kills. And so is--shazam--the macho (but secretly gay) Irish lieutenant cop who fired Mekkler in the first place. And the conspiracy? Pan-Jewish ""Frankists"" who believe ""the only way to rid the world of sin"" is ""to embrace sin."" Uh-huh. Mekkler finally decides to Forget It All and be a ""fag gun for hire."" Well, it's probably cleaner work than writing books like Down and Dirty.