PUSHING THE ENVELOPE

Reader beware: "Cloud Atlas" (509 pages. Random House) will likely be among the most exasperating books you will ever read. But swallow your frustration (and your urges to hurtle the book out the nearest window), and stick with author David Mitchell. You're in for a wild, wonderful ride.

Mitchell, who was a Booker Prize finalist for his last novel, "Number9Dream," pushes the fictional envelope in this, his third and most audacious work. He interweaves six separate narratives--each rich enough to stand on its own--into a book that incorporates five literary styles (including letters, a travel journal and traditional mystery writing), straddles four continents and spans several hundred years.

The journey begins in the mid-1850s with the tale of Adam Ewing, an American traveling in the Chatham Islands, a remote region of the Pacific. In a journal, Ewing records his adventures--skirmishes with the sea-hardened sailors and a halfhearted intervention on behalf of a runaway slave. But just as Ewing's story becomes engrossing, his diary comes to an abrupt end, interrupted in midsentence by another narrative set 80 years later on a different continent. The reader suddenly finds himself in 1930s Belgium.

In "Cloud Atlas," Mitchell does this again and again. He seduces you with his compelling characters and their narratives, and just as you're hooked on one story, he yanks the rug out from beneath your feet. Though it's hard to let go of one tale, it's thrilling to get immersed in the next.

It's also impressive to see how fluidly Mitchell moves between writing styles. Critics of his last two books complained that the author lacked a distinct voice. But why would a born mimic like Mitchell need one when he can imitate others' voices so perfectly? Whether speaking post-Apocalyptic pidgin English or the corporate-speak of a 22nd-century clone, Mitchell's dialogue is always pitch perfect.

Though "Cloud Atlas's" characters are marooned in their own time and place, they connect to one another through the act of reading. Robert Frobisher, an ambitious young composer living in Belgium between the two world wars, discovers Ewing's journal, and mentions it in his letters to his gay lover. These letters turn up again in California in the 1970s, as part of journalist Luisa Rey's investigation of a massive corporate cover-up. And so the chain of writers and readers stretches into the distant future. The fine threads that link the narratives multiply, and the stories become increasingly interwoven. In the hands of a lesser writer, this book would be, at best, the sum of its disparate parts. It's a testament to Mitchell's formidable skill and imagination that Cloud Atlas adds up to so much more.