In "Underberg," the 300-page opening section of Jonathan Lethem's sprawling opus The Fortress Of Solitude, every passage begins like the first page of a novel, working furiously to set a scene. Once it finally gains a foothold, the book slips away again, giving the initial impression that Lethem may also be losing his grip, unable to contain his runaway ambition. But while the messy, discordant rhythms of "Underberg" take some getting used to, they also add a special intensity to Lethem's vivid account of growing up in Brooklyn in the '70s. Filtered through the memories of young Dylan Ebdus, the author's hero and alter ego, this frightening transitional period unfolds like a fever dream, filled with powerful characters and feelings that have left their indelible mark on his adult life. Much like Michael Chabon's The Amazing Adventures Of Kavalier & Clay, which it resembles right down to the superhero and comic-book references, The Fortress Of Solitude gives a shadow history of New York, with real figures and events freely intersecting with fictional ones. Among other things, the allegorical title refers to a Brooklyn neighborhood now known as Boerum Hill, where Dylan and his parents reside on the cusp of gentrification, the lone white family on a crumbling, all-black street near the Gowanus housing project. The guinea pig in his hippie mother's social experiment–she brags that he's one of only three white kids at his grade school–Dylan faces the daily specter of getting "yoked" by his peers, who ritualistically tease him and shake him down for lunch money. After his mother leaves and his artist father spends every spare moment etching paint on film frames, Dylan's isolation grows even more pronounced, relieved only by time with his neighbor and best friend, Mingus Rude. His intimate, heartbreaking relationship with Mingus, the son of a coke-addled former R&B singer, gives The Fortress Of Solitude its haunted soul, especially as their lives spin off in tragically opposed directions. Once united as graffiti artists (and, in a peculiar stab at magic realism, as the duo behind a crime-fighting vigilante hero named Aeroman), Dylan and Mingus drift apart as the former inches toward a more privileged destiny. The back section of the book reads like a second novel; it switches radically from the impressionistic omniscience of the first half to the studied, first-person voice of Dylan, now a well-educated, 35-year-old music critic. Though deposited in faraway Berkeley, Dylan still hasn't mentally left the old neighborhood; he's clouded by guilt and sadness over the place's altered complexion, and over what happened to Mingus. The two oblong halves of The Fortress Of Solitude, divided by an inspired "liner notes" section devoted to Mingus' father, typify Lethem's kitchen-sink aspirations, smashing personal and urban history together with language that wildly evokes in the first section and pensively reflects in the second. A naked stab at first-tier recognition after Lethem's breakthrough novel Motherless Brooklyn, The Fortress Of Solitude is a vessel for the author's entire bag of tricks: It's flawed and unwieldy, yet shot through by a restless and vibrant imagination. Any time the result feels unsatisfying, it's only because a reach that long is doomed to exceed its grasp.