Tasked with solving a complicated country house killing in order to right a wrong, the protagonist must do so from inside a different body each day. Shades of Agatha Christie and Groundhog Day right enough, but I guarantee you will note more great parallels as you both enjoy and are frustrated by this amazing book.
Everything I saw that day, how much of it was real? Was anybody who they claimed to be? I believed Daniel and Evelyn were my friends, the Plague Doctor was a madman, and that I was a doctor called Sebastian Bell, whose biggest problem was a memory loss. How could I know those were merely the starting positions in a race nobody had told me I was running?