AD180: Quintus Suetonius and his stepson Manius are frumentarii, the Roman Empire's secret
police. Dispatched to Britannia on a mission whose purpose is kept veiled from them, they
join forces with the formidable female spy Tita Amatia and find themselves embroiled in plot, counter-plot and assassination, unsure of either their allies or their
enemies.

They journey from bustling, cosmopolitan, civilised Londinium to
the wild North - a hostile snowbound land.

Besieged by an alliance of rebellious local tribes, surrounded by
intrigue, assailed by matters of the heart and personal ambition,
they become reluctant players in a struggle between a ruthless
imperial government and others seeking control of the Empire.