This is the first of Randall Garrett's three immensely entertaining "Lord Darcy" books about a detective in an alternative history world where technology is based much more on scientific magic rather than the physical sciences.
The three books in the series are
"Murder and Magic"
"
Lord Darcy Investigates"
"
Too Many Magiciansand the whole series has been published in one volume as
Lord Darcy.
This book introduces the hero, Lord Darcy, special investigator to the Duke of Normandy, who is brother to his Imperial Majesty John IV, King of England and France, and Holy Roman Emperor.
The idea for the series is that King Richard the Lion Heart survived his injuries from the crossbow bolt at Chaluz, but that the effect of nearly being killed caused him to devote much more of his attention to the strength of his kingdom rather than exciting wars and crusades. In the process Good King Richard supposedly strengthened the Angevin Empire so much that instead of losing their position in France his successors not just held the throne of England but made their claim to the throne of France a reality. And seven centuries later the Angevin empire is the world's main superpower.
Richard living to old age also means no King John, and therefore no Magna Carta, so by the time of the alternative 20th century when these books are set, some rudimentary forms of democracy have developed but royal power in the Anglo-French empire is much greater than in real history.
And most significant, the "laws of magic" were discovered in King Richard's reign, and forms of technology based on the scientific application of magic have followed.
Randall Garrett had quite a balancing act to set a series of detective stories in such a world. What forensic magicians can do in these stories had to be different enough from the capabilities of forensic scientists in the real world to make the stories interestsing, but not so great as to render the job of a detective redundant. Had magicians been able to look back through time and see a crime, for example, or if they had magic spells which function as infallible lie detectors, there would be no detective challenges for our heroes to solve.
Garrett brings this off brilliantly, giving Lord Darcy's magician colleague, Master Sorceror Sean Lochlainn, a set of powers bound by rules not dissimilar in effect to the laws of physics, so that the information which can be gleaned by magic still leaves puzzles for the detective to solve which require intellectual skills similar to those needed by Miss Marple in the works of Agatha Christie.
One of the most unusual detective series ever written.