The Second Sleep by Robert Harris
Set in 1468 in a rural English village, the title is based on the idea that we sleep, then wake for a usable space of time, then sleep again. But what actually happens during that awake period? And is it 1468 as we know it? A young priest arrives in the village to conduct the funeral of his predecessor who had a very odd collection of ancient artifacts. Did these contribute to his death? An absorbing and thought-provoking thriller from a master of the intelligent thriller.