The Sarantine Empire is beset by enemies, but the Emperor Valerius II is determined to win Rhodias, Western cradle of the empire, back from the barbarians who overran it - and also to build the greatest Sanctuary to the god Gad ever created. Into this maelstrom steps Crispin, a master mosaicist who observes the power of the older gods at first hand, even as he journeys to fulfil the emperor's command. He will find colour, death and deadly politics at his elbow . . .