Rome: August 314 AD, and as the sun's insidious heat beats down, murderous forces lurk in the underbelly of the city. The normally cosseted world of Rome's rich and powerful is rocked by a series of violent abductions, as children of the elite are kidnapped and held for ransom. Meanwhile, veteran soldiers, men who served Constantine along the Great Wall in northern Britain are being barbarously murdered; the indignities inflicted on their corpses reminiscent of the gruesome practices of the Picts whom they fought so many years ago.

The Empress Helena summons her secret agent, Claudia, in a bid to resolve these macabre occurrences. But Claudia has problems of her own. The perfectly preserved corpse of a young Christian woman has been disinterred in her uncle's garden and it falls to her to investigate this mystery too. Now she must track her way through a murky tangle of politics, religion and murderous violence, ever aware that the slightest mistake could cost her life.