It is tempting to say fits into Pynchon's corpus by refusing to fit right in. It is, in certain respects, his most conventional and realistic novel to date. The parenthetical plot is confusing, dashing down any number of blind alleys on wild-goose chases after red herrings. When our heroine, Maxine Tarnow, exclaims, "Help, too byzantine, make it stop!'" the reader may well sympathise with this cheekily self-referential health warning about a plot that approximates the tribulations of crazy golf in narrative fiction. At the same time, is no more eye-straining than Raymond Chandler's The , James Ellroy's labyrinthine "Underworld USA" trilogy or Elmore Leonard's whimsical thrillers.

In the book proper, Maxine's cri de coeur rails against one of 's manifold conspiracy theories. The subject under paranoid deconstruction is September 11, which in the novel has occurred only a few days before. Maxine's personal theorist is March, a dyed-in-the wool leftie who is convinced the Bush family ordered the attacks. The evidence is a grainy DVD appearing to show a band of unidentified Americans firing Stinger missiles from the top of a New York skyscraper.

Pynchon's plot elevates the conspiracy theory to high art: how even the most ineluctable events shimmer under the 21st century's love affair with instant replay and instantaneous re-evaluation. Take that DVD of rocket-launching practice in New York. What exactly does it reveal? Maybe, March suggests: "Somebody planning to shoot down an airplane. Say, somebody in the private sector, working for the current US regime." Maxine responds: "Why would they?" Just when the reader smells some unsettling prophetic irony, March undermines the evidence before their eyes: the images can be tampered with, the date stamp altered. How can we possibly know what to believe in the face of such ambiguity? Pynchon pays the scene off on September 11 when Maxine's underwhelmed reaction - "Uh-oh" - misunderstands the full horror of the terrorist attacks.

Perhaps Pynchon's plan is to refine realism for an age where that concept, shaky back in George Eliot's day, has examined itself into near-nothingness. He works hard to lock down those hoary old orthodoxies such as time and place. New York is lovingly described. Every one of his dizzying allusions to films is accompanied by a date - except for and mysteriously enough.

Yet no matter his rigour, the concrete and the everyday are under constant threat - not just from filtration through cyberspace, but from dreams, Maxine's boozy, dope-filled late-nights, and the plot's fragile links between cause and effect.

In this context, morality is fluid and unstable: today's computer hackers are tomorrow's defenders of a nation. Any notion of an integrated self is precarious. Almost everyone in New York seems desperate to be somebody else: a young web designer wants to be Jennifer Aniston, a financier thinks he's a rapper. Avatars rule. Characters routinely conceive of people and relationships in movie terms.

For all its dizzying meta-critiques, is enormous fun. Pynchon's prose froths and floats like a scented bubble bath. Maxine's erratic ex, Horst, is "a fourth-generation product of the US Midwest, emotional as a grain elevator". His refusal to convert to Judaism inspires Pynchon to attempt some Jane Austen by way of the upper west side: "If it's a truth universally acknowledged that Jews don't proselytize, Horst certainly was and remains a prime argument for why not." There are silly hip hop parodies, and a glorious throwaway riff about Ikea: "blood already streaming from several fingers … mysterious metal and plastic fasteners littering the floor … Screaming."

Whether Pynchon proves a trial or a delight depends on finding meaning in the chaos. "Maybe you want to believe there is a connection," March tells Maxine. This injunction hints at the novel's triumphant marriage of playfulness and glittering surfaces to genuine emotion.

Pynchon writes with considerable compassion about the impact September 11 had on New York: how a city of "mutually disconnected lives going on in parallel" was united, however briefly, in grief and communal sympathy.

Nowhere is this more simply or warmly presented than in Maxine's interactions with her children, friends and even her errant husband in the days after the attacks: in the darkest of times, making a connection suddenly radiates with deeply felt human significance. deserves a place besides Pynchon's finest works. Just don't get lost in Byzantium.