Ancient Roman sleuth Marcus Corvinus is despatched to Gaul on a personal mission for the emperor.

June, AD 42. The emperor Claudius himself has requested Corvinus's help in investigating the murder of a Gallic wine merchant, stabbed to death as he was taking an afternoon nap in his summer-house at Lugdunum.

Not especially happy at being despatched to Gaul, and even less enamoured of his enforced travelling companion, the insufferable Domitius Crinas, Corvinus is increasingly frustrated as it becomes clear that the dead man's extended family and friends are hiding something from him. Unused to strange Gallic customs and facing an uphill struggle getting anyone to talk freely to a Roman, Corvinus is convinced that there's more to this murder than meets the eye - but, a stranger in a strange land, how is he going to prove it . . .?