Cassandra Clark's book is a cheat – but it cheats in the way that most authoritative historical crime fiction must. After all, any attempt to recreate the speech (and thought processes) of characters living in the 14th century has to be a conjuring trick that convinces us we're in the distant past, but doesn't render the language so archaic that it's impossible to relate to the characters.
Clark is one of the most sure-footed practitioners of this difficult genre. She treads a careful line between current language and persuasive-sounding period speech which reads as if it might have been spoken in 1383, when England is ruled by John of Gaunt.
This linguistic balancing act is only one of Clark's accomplishments; like C J Sansom in his Tudor series, she boasts the most precious skill a historical writer can possess: the ability to transport the reader into a distant era, corralling all the sights, sounds and smells of the past. Some may regret that her heroine, the nun Hildegard, is yet one more in the overcrowded ranks of ecclesiastical sleuths, but Clark makes the best possible case for her verisimilitude.
Hildegard is a widow, wealthy, educated and independent, but choosing to live as a nun. At a time when travel is a dangerous enterprise, she is sent from her base in Yorkshire in search of a priceless relic, the Cross of Constantine. Political turmoil is the order of the day in England, with the Crown at stake. Many would like to see Hildegard fail in her mission.
Since Ellis Peters and Umberto Eco started the medieval ball rolling, a slew of historical novelists have mastered such techniques. What distinguishes Clark in this sprawling, peripatetic narrative is the characterisation of her heroine. Again, Clark might be said to be cheating: a rich, tough and resourceful woman who survives much danger in the 14th century, and, what's more, is a nun? But such is Clark's dexterity that we are willing to accept the premise.