This story, set in what is now East Anglia, takes place during 449-451, after the departure of the Romans from Britain. During the Roman occupation, Mangan, a Briton, captured by a band of armed Romans, is forced to help bury several heavy treasure chests and then sold as a galley slave. Thirty years later, he regains his freedom and returns to East Anglia. But he is obsessed with the memory of the treasure which he helped to bury, and so, accompanied by his grandson, Cador, he sets out to try to find the place again so that the treasure can be used in the fight against the Huns, who are threatening to overrun the whole of Europe.

The dangers Mangan and Cador face, and the difficulties they have to overcome make this a fast-moving and thrilling story.