Book 4 in the Sword of Cartimandua series.

Julius Agricola has almost conquered Britannia but a jealous Emperor recalls him to Rome. Marcus' Horse and the Batavian auxiliaries are left to try to stem the tide of barbarian invasions from the fearsome Caledonii. Treachery and treason put the lives of the officers of Marcus' Horse in direst danger and they have to fight not only the enemy but traitors and witches.

A historical fiction novel by Griff Hosker.