That is the promising beginning of Greg Bear's 2010 novel Hull Zero Three, a thrilling, if somewhat opaque hard SF thriller. The protagonist of the story, Teacher, has no memory of his identity or knowledge of his purpose, only slowly learning that he has been reborn on an immense ship, a ship that appears to be doing its level best to kill him and all other humans.
"It's a ship," one of the characters he meets pronounces, "A sick ship."
Bear's best work combines a naturalistic touch for characters with speculation on truly epic scales. His early novels Blood Music, Eon, and Eternity, slip easily from straight-forward human drama to contemplations of phenomena stretching to the ends of time and the transcendence of human civilization. He wrote some of the earliest stories addressing the nanotechnology and a coming singularity (although he's never called it this, as far as I know).
Here, Hull Zero Three pulls the reader in two directions: outwards with a consideration of the staggering scale of the generation ship Teacher journeys through and inwards with a rumination on the nature of identity. Nothing in the book is terribly original; many, many authors have explored generation ships and the slippery nature of identity and duplication detailed in this story reminds me of the movie Moon. Bear has a talent for details: bewildering, bizarre, and strangely specific descriptions of water tanks the size of asteroids, monsters like crabs with lawnmowers for mouths, and the starship itself, which is on a scale difficult to fathom, let alone sketch out without having the plot bog down in an avalanche of explication.
Bear's careful husbanding of details and facts can become maddening. I'm currently rewatching LOST with my wife and its bread-crumb approach to revealing mysteries reminds me a lot of this book. People speak enigmatically about dark truths they assume the listener already knows or couldn't possibly handle learning about. Clues are left behind in tattered books and drawn on walls. One gets a sense very early on that no one can be fully trusted, not even the narrator. Framed narratives abound, as well as tricky flash-backs. Unfortunately, just like LOST, this is doubly true given the sense that the mystery, once solved, isn't going to be anywhere near awesome enough to justify the time spent investigating it.
While I think the book overall was a quick fun read for fans of hard sci fi, I wouldn't recommend to anyone except genre-fans. The story is well-told and engaging, but the ideas here have been better explored elsewhere, including in previous work by Bear.