Gnomon

In a near-future Britain, a distributed surveillance-democracy called The System knows everything about you: it can even spy on your mind.

Britain has, in effect, become a Panopticon country.

But when state investigators then look into the head of a refusenik novelist named Diana Hunter, what they find there is not her life story but that of four other people, spread across thousands of years, all vibrantly real and each utterly impossible.

But before they can unravel that puzzle, Diana dies as a result of the investigation - an unheard of occurrence in a perfect system which protects everyone from harm.