When Gaius Peterius Ruso rejoins his unit in the remote outpost of the Roman Empire known as Britannia, all is not well with the Twentieth Legion. A young soldier has jumped off a roof, killing himself, but no-one will say why. Mysterious injuries and even deaths begin to pile up, and it soon becomes clear that this suicide is not an isolated incident. Can the men really be under a curse?

Bound by his sense of duty and ill-advised curiosity, Ruso asks questions nobody wants to hear while his barbarian wife, Tilla, starts to find some of the answers – and is marked as a security risk by the very officers Ruso is interrogating. 

As the charismatic Emperor Hadrian and his distinctly unimpressed Empress Sabina finally arrive for their long-awaited visit, the fates of the Legion, Tilla and Ruso himself hang in the balance.