Rachel Cusk is one of literary England’s better-kept secrets: She is a concealed pen knife. Small in scale, her novels demand attention, incisively sketching the increasingly crass manners of Britannia. “In the Fold” (Little, Brown, 262 pages, $23.95), Ms. Cusk’s fifth novel, affords literary pleasure as it is imagined: in an armchair, chuckling.

The novel begins with a classic setup: Adam Hanbury is driving Michael, the perspicacious narrator, to visit Egypt, as the Hanbury estate is called. The English country house slowly unfurls its dark and lovable secrets, and spoiled children hurt one another other off-stage. As Michael watches Adam revert to the arrogant joy of his familial seat, something changes – “wholehearted acceptance becomes slowly interred in recrimination.” It is a process with which he becomes familiar – in Chapter 2 he finds himself middle-aged, living with a woman he no longer loves, wondering why he hasn’t talked to the Hanburys in five years.

“In the Fold” borrows some of the “Brideshead Revisited”-style power dynamic employed so skillfully in Alan Hollinghurst’s recent “Line of Beauty,” in which a sensitive young boy tries to join a slightly more worldly, twisted family. But the keynote of Ms. Cusk’s novel is Michael’s passivity, which makes the author’s humor possible. It contains contradictions, double exposures that express the hilarity of comparing middle age with youth.

At its best, Ms. Cusk’s writing exaggerates and lies, for your pleasure: “The pale silky material of her dress and her light-toned skin and hair gave her a formless, undulating appearance,” Michael writes of his weeping wife, squinting for the reader’s comic benefit. “The impression she gave now,” Michael writes of a young Hanbury now grown up, “was one of striking beauty, which, curiously, solidified almost immediately into the certainty that she was not beautiful,” as if aging were an instant of indecisiveness.

Though “In the Fold” ends on a serious note – Ms. Cusk goes so far as to compare middle age to the “spoliation” of a classy old town – its sentences suggest that aging is not a tragedy so much as a slow and sometimes hilarious gag.

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Rafi Zabor’s imaginative memoir, “I, Wabenzi” (Farrar, Straus, and Giroux, 480 pages, $26), exemplifies the congenial, bozo spirit that has repeatedly overwhelmed our most solemn literary forms. A Jewish jazz drummer who became a whirling dervish, Mr. Zabor does not hesitate before the superficial mystique of things; he goes right in and plays on the keys. Against the obsessive-compulsive fragility common in memoirs, compare Mr. Zabor’s showmanship: “The reader,” he writes, “may already have recognized the dishonest compensatory note sounding amid the heartfelt, reverent music that plays whenever I write about my fathers.”

Mr. Zabor’s writing sometimes sounds like post-conversion revisionism, and even when he expresses his doubts about Sufism, with its fiery visions and transcendent dance routines, he still retains the language of the enthusiast: “And what about the possibility that with all our lines of light and huffa-puffa we were only dialing up cartoons on our nervous systems?” Huffa-puffa, indeed: No matter how specific Mr. Zabor’s esoterica, he remains a pilgrim of Brooklyn, informed by the collaborative ethics of jazz.

Like a jiggling Neapolitan cheesecake, the book’s tripartite flavor – immigrant’s child, jazz hipster, European Sufi – appears both absurd and delicious at the volume’s beginning. But by its end, after Mr. Zabor has fully demonstrated his mastery of the elliptical and rhythmic non-narrative flow, it appears as the incidental material of a technical masterpiece.

Mr. Zabor, with his big mouth and free-skidding brain, looks like a literary ideal, more so because his enthusiasm is not quite believable. His innocent deployment of collegiate words – “I was from birth headstrong, willful, purblind, stubborn, wrongheaded and as difficult to lead as any fractious horse” – his addiction to inside jokes, like the one in which Western Civ becomes “Western sieve,” and his aw-shucks self-consciousness approach obnoxiousness, and dare the reader to turn up his nose. But Mr. Zabor is persuasive in his wonderment: “Where was this stuff coming from?” he asks, after seeing a vision. He belongs not just to the tradition of American writers but to the tradition of American salesmen – street vendors, preachers, buskers, comics.

The “Wabenzi” of the title refers to an African expression for owners of Mercedes-Benzes. Mr. Zabor aspires to join this class, though he doesn’t get to buy the car in this volume, the first of a projected four. “I, Wabenzi” is vivid, amplified, and searching. If Mr. Zabor’s autobiography lacks the critical moment of self-alienation on which book loving faith depends, it may be because these hundreds of pages – which are subtitled “Aporia” – barely represent a breath of Mr. Zabor’s story.

blytal@nysun.com