The crows are gathering above Glasgow, watching the movements of the clergy and townspeople alike...

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. And then there is another death. How is it connected to the first? While his wife Alys deals with the tensions within their family, Gil has to untangle the threads of the mystery to find the solution to all the crimes.