David Mitchell's Cloud Atlas is this year's literary jazz solo: an ambitious roller-coaster ride through cycles of imagined history that jets up one side of six stories and then down the other, with tongue in cheek and heart on the sleeve.

Think of boxes within boxes within boxes — six related stories, ranging from the far past to the further future, each evolving from the other. Or, more to the point, think of a pyramid, because it has the symmetry of one: five half-stories on one side mirrored by their endings on the other, with one "whole" story at the apex: one, two, three, four, five, six, five, four, three, two, one, so to speak. Like any good game, you understand this more as you play it.

It begins with a diary, set in 1850. Adam Ewing, a notary traveling by ship from Sydney to his home in California, is temporarily stranded in the Chatham Isles near New Zealand. Like the typical naif in Melville's early novels, Adam is an innocent whose Pacific journey opens his eyes to the horrors committed in the name of civilization, namely the way the white settlers have used the Maoris to enslave the peace-loving Moriori people. Adam takes mysteriously ill and, while attempting to recover, saves a Moriori stowaway from death; suddenly — boom — his journal stops mid-sentence.

We move ahead to another place altogether: Germany, 1931, where a carefree, bisexual English composer named Robert Frobisher is writing letters home to his friend Sixsmith. Heavily in debt, Frobisher takes a job helping a selfish old composer complete his unfinished symphony, Eternal Recurrence, which basically means writing it for him. In his off-hours, Frobisher discovers a bound version of The Pacific Journals of Adam Ewing. Unfortunately, the book has been torn in two and he can't find the other half; "the pages cease, mid-sentence."

Frobisher's letters likewise stop suddenly, but the game of eternal recurrence continues apace. We bolt ahead to California in 1975, where Sixsmith is now an atomic engineer and would-be whistleblower at the nuclear facility of Seaboard Corporation, trying desperately to get someone's attention about the dangers of the company's latest reactor. Sixsmith tries to pass along his own suppressed report on the reactor to an investigative journalist named Luisa Rey, who becomes drawn into Sixsmith's past, intrigued both by the letters from Frobisher 40 years before and that late composer's little-known "Cloud Atlas" symphony.