Cloud Atlas, by David MitchellRead about the other entries on the list.
Cloud Atlas is structured as nested stories sharing reincarnated characters, either repeating the fate of their previous selves or rebelling against them. The characters’ souls undergo various transformations as the timeline advances—but that advancement is difficult to follow, as each story is interrupted at a key moment, at which point, the next story begins—until we get to the sixth, central story. From that point on, each of the first five stories is continued, finishing each narrative. The connections between the stories go far beyond the characters, making this one of the densest and most complicated narratives of all time, a structure the movie version couldn’t even begin to replicate.
Cloud Atlas is among Christopher Priest’s top five science-fiction books that make use of music, Patrick Hemstreet's five top books for the psychonaut and the six books that changed Maile Meloy's idea of what’s possible in fiction.