My Detachment, the title of Tracy Kidder's new memoir of his year as a soldier in Vietnam, carries an unstated double meaning.

On the surface, it refers to the eight-man unit he commanded - fresh out of Harvard's ROTC in 1969 - with the 509th Radio Research Group while stationed away from the battle lines in a place called Chu Lai.

But the title could just as well refer to Kidder's state of mind. While he busied himself with the task at hand, mapping the radio communications of the North Vietnam Army, Kidder was, at most, ambivalent about the war and his role in the military.

Similarly, this is a somewhat ambivalent book: hilarious in some details of his backwater assignment, unsparing in his assessment of his F. Scott Fitzgerald-inspired Gatsby-like self-image, but, in the end, rather meaningless.

There doesn't seem to be much of a point to his story, other than to document the foibles and self-delusions of a unit where the main pastime seems to consist of drinking a lot of beer, an occasional foray to the whorehouse and watching episodes of the World War II-set television show Combat.

The chief fear here is not of physical harm from an unseen enemy but the dread of an inspection from the military brass.

This is not Kidder's first Vietnam book. As a young man, he also wrote an unpublished novel about the war in which his protagonist, a stoic young lieutenant, dies tragically, killed by his own men.

Kidder resurrects parts of the novel, titled Ivory Fields, in this memoir. Judging by the excerpts, there's good reason why his fiction never got published: It comes across as mawkish and melodramatic.

His recycling of this material is one of the more annoying aspects of the memoir. So, too, is his use of his letters home, many of them never sent, which give a largely fictional account of his experiences.

The book does manage to be hilarious in an anecdotal way. There's an episode, for example, on how a pain-in-the-butt soldier named Pancho manages to lose a top-secret document caught up in the whirlwind created by a helicopter. But, ultimately, stringing together anecdotes does not constitute a compelling narrative, no matter how funny or true.

This is unfortunate, because Kidder is an excellent writer. His earlier book, Hometown, was a marvelous work of book-length journalism.

This, however, is not one of his better books. The reader will finish it feeling, well, detached.

John C. Ensslin is a staff writer with the Rocky Mountain News.