Follow on to The Wall (that I would recommend reading first as it puts much into context).
Roman cavalry commander Marcus Flavius Victor abandons his post in Britain and takes a small band of troops on a mission to rescue his son in Saxonia. His son is, indeed, rescued but their escape is cut off and Marcus finds himself in unfamiliar territory and with a son who seems to hate him. His only option might be to try and find his way to his old friend General Stilicho who is hundreds of miles away and it would be a dangerous journey. Stilicho is, meantime, trying to defend Italy against a vast invasion by Radagaisus, King of the Ostrogoths.
Much to enjoy in this. The era is interesting AD406, Roman power and traditions are diminishing, and the old religions are being replaced. “Barbarian” tribes sense a weakness in the Roman Empire under the feckless Emperor Honorius and the Roman Empire is on the back foot. I very much enjoyed this sense of a changing time and the reminder that most “Roman” troops were from conquered nations, with the conflict of Roman arrogance and disloyalty playing against brotherhood.
Minor quibbles might be that his son stops hating him very quickly indeed and Marcus falling for a female slave felt a bit odd in the circumstances.
There is a lot in this, far more depth and sense of time than most “sword and sandals” and delivered by a talented author who really does know his stuff.