February, 1381. London lies frozen in the grip of one of the bitterest winters on record. The ever-rising taxes demanded by the Regent, John of Gaunt, are causing increasing resentment among the city's poor. When the seething unrest boils over into a bloody massacre at a splendid Southwark tavern, The Candle Flame, in which nine people, including Gaunt's tax collectors, their military escort and the prostitutes entertaining them, are brutally murdered, the furious Regent orders Brother Athelstan to get to the bottom of the matter.

For not only has Gaunt's treasure trove been stolen, he has reason to believe a French spy is active along the Thames, carefully recording for his masters in the Louvre the state of English war cogs. And a professional assassin, Beowulf, who has sworn vengeance against Gaunt and his minions, also stalks the shadows. Once again, Athelstan must enter the murky world of murder, where the darkness constantly shifts and no one is who or what they seem.