All that keeps No Country for Old Men from being a deftly executed but meretricious thriller is the presence, increasingly confused and ineffectual as the novel proceeds, of the sheriff of Comanche County, one of the "old men" alluded to in the title.

"No Country for Old Men" is an unholy mess of a novel, which one could speculate will be a bitter disappointment to many of those eager fans. It is an unwieldy klutz that pretends to be beach reading while dressed in the garments of serious literature (not that those are necessarily mutually exclusive concepts). It is a thriller that is barely thrilling and a tepid effort to reclaim some of the focus and possibly the audience of McCarthy's most reader-friendly novel, "All the Pretty Horses." Worst of all, it reads like a story you wished Elmore Leonard had written -- or rather, in this case, rewritten.

Mr. McCarthy turns the elaborate cat-and-mouse game played by Moss and Chigurh and Bell into harrowing, propulsive drama, cutting from one frightening, violent set piece to another with cinematic economy and precision. In fact, ''No Country for Old Men'' would easily translate to the big screen so long as Bell's tedious, long-winded monologues were left on the cutting room floor -- a move that would also have made this a considerably more persuasive novel.

In the literary world the appearance of a new Cormac McCarthy novel is a cause for celebration. It has been seven years since his Cities of the Plain, and McCarthy has made the wait worthwhile. With a title that makes a statement about Texas itself, McCarthy offers up a vision of awful power and waning glory, like a tale told by a hermit emerging from the desert, a biblical Western from a cactus-pricked Ancient Mariner.

Cormac McCarthy's ''No Country for Old Men'' is as bracing a variation on these noir orthodoxies as any fan of the genre could expect, although his admirers may not be sure at first about quite how to take the book, which doesn't bend its genre or transcend it but determinedly straightens it back out.