Although he was watching closely when the mummer was poisoned, it took Gil Cunningham several days and three more poisonings to work out how it was done. Danny Gibson and Nanty Bothwell, rivals for the affections of Agnes Renfrew, the apothecary's pretty daughter, are also good friends.

Gil Cunningham had hoped that the first time he set foot in the brothel on the Drygate it would also be his last, but by the time all was settled he felt quite at home within its artfully painted chambers. The bawdy house, along with the neighbouring property and two more in Strathblane, are all part of a deal offered to Gil and his wife Alys by the forceful Dame Isabella.

Tied to St Mungo's Cross by the cathedral to be cured of her madness overnight by the saint, the young woman is found in the morning beaten and strangled, still tied to the cross. But is she who she seems to be? And who would flout the saint's protection like this? Gil Cunningham must trace the dead woman and find her enemies, track down the thieves and murderers and identify the watchers in the shadows, particularly the elusive fourth person who holds the secret of what happened that night. Questioning cathedral staff and apprentice boys, pilgrims and tradesmen, he uncovers only more puzzles.

The tenth story in the popular Gil Cunningham series set in medieval Glasgow. 'The tale seems very improbable,' Gil Cunningham said. 'How should the Devil enter a religious house and carry off one of its members?' How indeed? But Arnold Fleming, the widely dislike pensioner, or corrodian, lodged in the Dominican's house in Perth, has vanished from a chamber, and a local knight and his mistress claim to have seen the Devil abroad that very same night.

The barrel should have contained books - instead it held treasure and a severed head...Gil Cunningham and his old acquaintance, Glasgow merchant Augie Morison, expecting a delivery of books from the Low Countries, report the gruesome substitute to the Provost, and at the inquest the next morning Morison is accused of the murder and imprisoned. He appeals to Gil, who sets out with his friend and future father in law Maistre Pierre, the French master-mason