BOOK REVIEW / HUMOR : One-Liners Add Only Flavor, Not Weight : THE PARTISAN <i> by Benjamin Cheever</i> . Atheneum: $21, 261 pages

When Benjamin Cheever’s first novel, “The Plagiarist,” came out, readers were happy to find that Cheever had not only inherited the writing skills of his father, the illustrious John Cheever, but had developed a distinctive voice of his own.

In this second comic novel, Cheever again shows himself a writer of considerable dexterity, but here he has fallen victim to either the sophomore slump or the temptation to revive a bottom-drawer manuscript.

Although “The Partisan” is entertaining page by page, it meanders hither and yon in search of purpose and ends up as a coming-of-age novel filled with wistfulness.

That’s not to say “The Partisan” lacks a center, however, for it is built around the formidable presence of Jonah Collingwood, a prolific, respected, occasionally charming and perpetually underfinanced novelist. He lives with his wife and two children, Nelson and Narcissus, in a small rented house on the park-like Rockefeller estate in Westchester County, N.Y. He is not, however, the head of a happy suburban household.

He insists, for one thing, that his children are not his own.

When Nelson, in second grade, tells Jonah that a fifth-grader has called him a bastard, Jonah makes a point of looking the word up in a dictionary and informing Nelson that his schoolmate “got you dead to rights”; Jonah also refers to Nelson and Narcissus as “SPCA” and “fire-sale” babies because they were unwanted at birth, adopted by Jonah’s sister-in-law and passed on to the Collingwoods so they could attend Westchester schools.

Nelson, narrating the novel as a college-student-cum-newspaper-tyro, knows the cloudy nature of his parentage, but it turns out to be even more complicated than Jonah has let on.

Nelson works for a local giveaway weekly, and “The Partisan” begins with Nelson taking a classified advertisement from a mysterious doctor.

Before long, the doctor, John Gilbert, is at the Collingwood home befriending Nelson’s father; he eventually reveals his intention to become Jonah’s biographer.

Cheever here is on to numerous comic possibilities--Jonah deceiving Gilbert, Gilbert transforming Jonah, Nelson revenging himself on Jonah through Gilbert, or something along those lines--but he develops only one, and not to a significant degree: Gilbert betrays Jonah, predictably and offstage.

Cheever explores more expansively Nelson’s infatuation with a girl who doesn’t care for him and his camaraderie with an office mate who does, but these sections of the novel, although often charming, are nonetheless evanescent.

Sometimes the father/son, boy/girl themes meet--after retrieving one of Nelson’s unsent, maudlin love letters from the wastebasket, Jonah begins lecturing Nelson about women by saying, “I may not know much about love, but I do know something about prose”--yet most of the time they float freely, pulling the novel apart rather than drawing it together.

It would be too harsh to characterize “The Partisan” as a series of humorous scenes stitched together with elaborate one-liners. But those lines are, in fact, the most memorable parts of the novel: Nelson, for example, says he wants to be a writer because on Judgment Day the “choice of words is going to be crucial.”

There are many moments like that in the novel, but ultimately, they don’t add up to much.