Back to the Buddy Shop : RULES OF THE ROAD <i> By Lucian K. Truscott IV (Carroll & Graf: $18.95; 336 pp.)</i>

Lucian K. Truscott IV--the grandson of one of the most honored American generals in World War II and the son of a West Point-educated officer--made significant literary waves in 1978 with “Dress Gray.” His suspenseful tale of the cover-up of a homosexual cadet’s murder at the U.S. Military Academy became a best seller and was made into a TV miniseries, scripted by Gore Vidal.

Beyond the conventional murder-mystery plot line and because Truscott IV himself was a West Point graduate (1969), albeit a rebellious one, “Dress Gray” could be seen as an indictment of quietly sanctioned brutality at this hallowed institution and the perversion of its honorable tradition. Published in the choppy wake of the Vietnam War and thanks in large part to the author’s pedigree, this compelling book received great media attention, and Truscott was allowed to bask in his 15 minutes of fame.

Naturally, back then, great things were expected of Truscott. Since “Dress Gray,” though, he has published only two other novels: “Army Blue,” a forgettable Vietnam novel and three-generational military saga, and the new “Rules of the Road.”

Truscott is in familiar olive-drab territory here, although his protagonist--a tough Army major and former stock-car driver named Sam Butterfield Jr.--ventures far enough away from the barracks to be drawn into a weird web of civilian mayhem. “Rules of the Road” is filled with car chases, old girlfriends and pesky moral dilemmas, so it reads very much like the kind of adventure favored by Hollywood studios these days.

En route from Germany to Ft. Campbell, Ky., Butterfield stops at the southern Illinois farm of his mother to sell his beloved “modified” racing car, a transaction he is talked out of. The major decides to head on to the base by bus and, at a rest stop, breaks up a fight between two sets of hoodlums.

This inadvertently puts a target on Butterfield’s back, as he finds himself smack in the middle of a vintage Land of Lincoln political scandal and an unlikely alliance with a colorful pool-hall pirate named Johnny Gee. To get out of their mess, Butterfield and Gee enlist a black enforcer nicknamed Moon, a prostitute who caters to state-house types, a childhood sweetheart, Mom, and the audio-visual department of Ft. Campbell.

In short, “Rules of the Road” is an odd-couple buddy film (on the order of “48 HRS.”) waiting to happen.

Like all such movies, this book relies on the chemistry of its two main characters for its appeal, and Truscott has built in plenty enough to satisfy. The Army-base scenes are well drawn, and Johnny Gee, providing a solid counterpoint to Butterfield’s gung-ho good-guy persona, continuously reveals unexpected levels of intelligence and sensitivity.

They combine to work a scam against the politicians who are threatening their lives for uncovering a blackmail scheme that would illegally benefit everyone from the governor to the county dog catcher. The action is fast, at times furious, and it effectively takes the reader on a romp through the rural back roads of the Midwest.

Also, however, like most buddy films, this action tends to disguise a plot that is strewn with giant potholes of implausibility--especially a satellite-video-piracy scheme that could just as well have been invented by an imaginative but uninformed 16-year-old.

It would be nice to say that, with “Rules of the Road,” Lucian K. Truscott IV has returned to form. It’s an amiable book, all right, and potentially one that could make a few bucks in a cinematic incarnation, but it’s hardly the comeback vehicle that will fuel a return to the best-seller lists.