It's an unusual and inventive premise for a mystery novel. A detective is confined to a hospital bed following an accident incurred pursuing a suspect. He is restless and bored; and he doesn't want to read because he finds contemporary fiction predictable and unappealing. Problem solving is more in his line, and so he decides to occupy his mind and his time in applying the modern policing methods of investigation and crime-solving to the historical and real-life mystery of the princes in the tower.
As premises go it's fairly ambitious. Conventional mystery novels exist in a world of certainty: authors can impose constraints to ensure this. The number of suspects, motives and clues is limited, and over the course of the story all the clues can be revealed, potential suspects can be eliminated one by one, and it is possible to deduce a single correct solution. But the real world is not nearly so certain. Police are fallible, and so are their methods: crimes go unsolved, innocent people get arrested. Solutions depend on how many clues have been uncovered, and how is it possible to know how many remain undiscovered?
Push the real-life problem back in time, and the uncertainty increases dramatically. Now we must depend on an even smaller sample of clues - those which made it into the records and then survived through time. And there is the additional problem that the actual truth is now unobservable, and any analysis must be speculation. There is no way of knowing how close any hypothesis mirrors the actual events. It is like trying to infer the picture on a jigsaw puzzle from a random handful of the pieces. The uncertainty is unavoidable. So having taken on such a daunting task, I was intrigued as to how Ms Tey would deal with all this uncertainty.
The answer is that she ignores it completely. She makes a considerable fuss over the fallibility of historians, and of the historical record. There are several places in the book where she goes so far as to deride them. The title itself is a reference to this fallibility: truth is the daughter of time, not authority. But there is no mention at all of all the other sources of uncertainty, particularly the fact that modern policing methods are by no means guaranteed to reveal the truth.
And this is the great flaw in the book. She is an author with a mission, and that mission is to rehabilitate the reputation of Richard III. And like every author with an agenda, that agenda acts as a filter. The details that support her case are allowed to flow through and make it into this book, those that don't are quietly ignored. The entire book and the investigation is predicated on the assumption that Richard was innocent of the crime. It is almost hagiographic.
I want to stress that I am not criticising the historical case she presents. I have no competency in that regard, because my knowledge of Richard III is restricted to Shakespeare's play. But I do take issue with the way she builds her case. It is a literary sleight of hand, almost a text book case in how to manipulate the reader. And where the medium of delivery is suspect, so must be the case.
Derision in an argument is always a bad sign. The first victim of this derision is Thomas More, invariably referred to as "the sainted Thomas More". Perhaps he did have an agenda, as he was part of the Tudor establishment, but given that he was martyred for refusing to back Henry VIII's plan to break from the Pope it is difficult to sustain the case that he was unprincipled. I allow that he may have been wrong. His great crime seems to be to have written the biography of a man 26 years his senior. But is this so unusual? Are biographers always the exact contemporaries of their subjects? He is treated as though he pretended to be an eye-witness to a crime, but was later revealed to be elsewhere at the time.
The second attempt at discrediting Thomas More seems mischievous. It is conceded that he was a Great Mind, but then we are reminded that Great Minds are sometimes wrong, particularly when they tackle subjects outside their speciality. We are virtually pushed in the direction of a logical fallacy. Some Great Minds are wrong sometimes. Thomas More was a Great Mind. And so what? Presumably we are meant to infer that Thomas More was wrong sometimes, but it doesn't follow. The fact that some Great Minds are wrong sometimes tells us nothing about an individual Great Mind.
There is no doubt that written records can be wrong, but you can't have it both ways. In this book written records are written off when they don't support the case, and relied on when they do. Sometimes events and actions are interpreted using 20th Century sensibilities, and sometimes in their medieval context. The possession of a motive is freely interpreted as a likelihood that an individual committed a crime, even though it is standard fare in detective novels that people with motives are not always guilty. And the derision!. Look at the quote above - if you as the reader don't accept the whole argument uncritically, then you are derided as well.
So read this book critically, and with your eyes open. I come away concluding neither that Richard III was guilty or innocent - only that it is impossible to know, and someone's fervent belief one way or the other cannot alter that simple fact.