The Fortress of Solitude by Jonathan Lethem

Tom Sawyer and Huckleberry Finn as two middle-aged losers

In an understandably patriotic period in US history, it's apt that leading lights of American fiction such as Jonathan Franzen and Aleksandar Hemon are infatuated with the concept of home. And now it's the turn of Jonathan Lethem. His latest novel, The Fortress of Solitude, a magnum opus that arrives lauded by the American press, focuses its macro-lens on Brooklyn where the author has lived for most of his life. The result is a huge, meandering and ambitious novel that proves he's one of the most fascinating and entertaining writers working Stateside today.

This isn't the first time he has written about the city. His 1999 noir thriller, Motherless Brooklyn, was awarded commercial and critical success along with a film contract from Edward Norton. Genre fiction is a handy vehicle for Lethem's linguistic skills. The Fortress of Solitude is no exception, lacing the coming of age saga with sci-fi allusions and a riff on music biography. Among the dealings of a Dickensian cast of hoods, hip hop artists and crack peddlers, the central tale concerns the friendship between Dylan Ebdus and Mingus Rude, two adolescents growing up among the commotion of 1970s Dean Street.

Even their names are signifiers: Dylan the sensitive white lad blowing about in the neighbourhood wind, Mingus the black rude boy pulsing with energy and action. At the beginning Dylan is little more than the local geek, orbiting his dysfunctional family (auteur-artist dad, hothead mum) in the search for escapism. Then Mingus arrives like an "exploding bomb of possibilities", complete with a Motown-star for a father and enough pluck to be friends with the only white boy in school.

Boerum, their corner of the city, is in a period of transition. Isabel Vendle, local bigwig and cranky old crone, tirelessly battles to mould the area into a Brooklyn version of Hampstead. Isabel, one of many superbly detailed minor characters, is as shackled by her warped vision of the future as Miss Havisham was by her obsessive reruns of the past. Her shot at gentrification misfires badly. Dean Street had "produced its own weird spore and she couldn't track or account for what bloomed now". In fact, instead of a hub for the professional middle classes Boerum becomes a "Bohemian grove", bookended by the grim council-run "projects" and the Puerto Rican community.

Street politics are a precarious business for Dylan. A trip to the corner shop becomes a green mile for a white boy walking: each errand a gauntlet of "yoking" (trousers hoisted, arms bent and cash liberated). Mingus is the antidote. The ludicrous nature of race relations is captured with intelligence and honesty. It's both simple and complicated: a matter of black and white until the grey element of friendship intervenes. Dylan and Mingus forge an alternate universe of comics, graffiti tagging and slang. They're fuelled by an obsession with superheroes and the chance of making a mark on more than the alley walls. It's a bond that sees them through the endemic rise in drug crime and flights of fancy to the more prosaic territory of the coming decades.

This is a beautiful but flawed epic. The first section of the book is so vibrant that the latter, set in the apathetic Nineties, can't help but disappoint. It's like finding out that Tom Sawyer and Huckleberry Finn ended up as bitter thirtysomething losers. And then its sheer length prompts two questions: does any novel really need to be as thick as a tree trunk, and do editors actually edit any more? However, these are minor criticisms. Scribbled notes in the margins of my copy left it as graffitied as the back streets of Boerum. There's something on every page to make you laugh, consider or wince in recognition. It's a big warm bath of a book that immerses the reader in the hustle and ghetto-blasted banter of the block. Soak it up.