An earth tremor near Bath exposes what the discovers to be its cause, a secret 'mine field' in the Roman-Celtic underground. They work out from digs and a Victoran manuscript it's all linked with Roman military commanders Marcus Quintanus and Cassius, Britton insurrection queen Baudicca ('Boadicea') and complex treason and cover-ups. But the danger is worse then appeared.—KGF Vissers