After a series of bloody battles, Camulodunum (modern-day Colchester) has fallen to the invading Roman army. The Emperor has returned to Rome, leaving the fearless Centurion Macro and his young Optio, Cato, to rest and regroup, along with the rest of the Second Legion. As their leader General Plautius plans the next phase of their campaign, word arrives that the ship carrying his family to join him was wrecked in a storm off the south coast. His wife and children have fallen into the hands of a dark sect of Druids, who now demand the return of those of their brotherhood taken prisoner by the Romans. Unless their demands are met within one month, Plautius's family will be burned alive. Will Cato and Macro discover where the Druids are hiding their hostages? And can they find some way to rescue them before time runs out?