This is a locked-room murder mystery which well upholds the traditions of the detective genre; if you like detective stories, you should get on well with this one. The author doesn't cheat; if you like trying to guess the solution ahead of the detective (I don't), you can reasonably have a go at it.
It has its unusual aspects, because it's set in an alternate world, one whose history diverged from ours in the year 1199. In that world, Richard the Lionheart wasn't killed by an arrow at Chaluz, but went on to reign for another twenty years, and was succeeded by his nephew Arthur, brother John having died in exile. Richard and Arthur retained and expanded their lands in France; and, by the twentieth century, the Anglo-French Angevin Empire encompassed not only Britain, France, and Ireland, but also North and South America. Furthermore, in the fourteenth century Sir Hilary Robert had worked out the laws of magic, putting the subject on a scientific footing, and the physical sciences as we know them were thereafter relatively neglected.
But this is mere background. The crime is the meat of the matter; and it's investigated by the redoubtable Lord Darcy, Chief Investigator for His Royal Highness, Prince Richard, Duke of Normandy; and the plump and cheerful Sean O Lochlainn, Fellow of the Royal Thaumaturgical Society and Chief Forensic Sorcerer to His Royal Highness. There are several murders to consider in the course of the book, and the affair is complicated by an issue of Imperial security arising from the suspected involvement of agents of the Polish Empire.
This novel is complemented by two volumes of short stories, Murder and Magic (1979), and Lord Darcy Investigates (1981). The stories are in much the same vein, worth reading if you like the novel (some of them in fact pre-date the novel, others were written much later). Purists offended by the intrusion of magic into the detective genre may like to know that most of the crimes in these books were committed by ordinary, non-magical means; magic is mainly used as an investigative aid, and as a source of red herrings.
Originally published in Thurb 5 in February 1985
October 2006: all the Lord Darcy stories are now available in one low-priced volume, called simply, Lord Darcy.
April 2007: See also A study in sorcery.