Cloud Atlas by David Mitchell for terribly obvious reasons. My entire family had read it years before, but it took the release of a trailer for the new film to make me finally pick the book up myself. I would be careful about watching the trailer before you have a go at the book itself since the characters in it are so wonderfully diverse and interesting that it is better to be able to enjoy them without flashes of Tom Hanks and Halle Berry's faces obscuring your imaginative vision. No one wants flashbacks of Cat Woman at the best of times, let alone when you're trying to unravel a challenging novel such as Cloud Atlas.
If you have already seen the trailer, then do not despair, as Mitchell is a wonderful craftsman and the characters become so real throughout the narrative that it's easy to forget the film, the actors, indeed even the fact that you have a cup of tea quickly going cold next to you. I am in awe of Mitchell in the same way I am in awe of Joseph Heller, because their books are written in such a manner that it is almost impossible to see where they could have started. I have no idea how Cloud Atlas was written, just as the seams and stitches that hold Catch-22 together are completely invisible to me. It is impressive to read. The strength of the novel lies in its characters who, though not all instantly likeable, are able to draw the reader successfully into their consciousness and into their world view. As one example, when you are first introduced to the character of Timothy Cavendish most readers will find him unpleasant at best. However, after his incarceration in a ghastly nursing home, he managed to change my mind and I could not help but urge him forward in his struggle. I rooted for him despite his alarming misogyny and pig-headedness, and ultimately loved him in spite of himself. Characters such as this make a challenging structure like the one Mitchell uses worth overcoming.
The structure is essentially of six narratives that are set hundreds of years apart on different continents with numerous characters that have tenuous literary-based links. It sounds confusing, but the beauty of it is that it really isn't. Mitchell guides you through the first half of every story, breaking off at a tantalising junction in each and launching you head first into a completely new environment and a brand new set of characters. Then, as you continue, you discover the conclusions of each story one after the other only to find that the stories were in fact about the same things all along. I will leave you to discover exactly what those are.