Alastair Reynolds, House of Suns, Gollancz, 2008.
This is a far-future novel combining big themes and the personal story of the main characters. The background story, told at the start of each section of the book, tells of Abigail Gentian, who became one of the first people to establish a Line, by creating a thousand clones of herself, with her memories, whose purpose is to explore the universe over thousands of years, and regularly meet up and share memories. These "shatterlings" differ from Abigail to some extent, so half of them are male and half female, and their appearance varies. From the moment they start their separate voyages, they become different people, and the regular meetings help them pool their memories and experiences.
Two of these shatterlings, Campion and Purslane, fall in love, something frowned upon within the Gentian Line. They are late returning to the meeting place for the reunion, and discover that someone has attacked the meeting place, killing most of the Line. The story follows the few survivors as they try to work out what has happened and who among them is a traitor. The survival of the Line is at stake, and the tensions between the survivors complicate the investigation. They are joined by some visitors, and the Machine People among them play an important role in the mystery, which turns out to be far larger and more important than anyone could have imagined.
This is a complex, exciting and touching story, with sympathetic characters and a satisfying ending. It is well-written, carefully paced, and engaging. I would welcome further stories set in this universe, which seems to have great potential.