Viv remembers a lot of things. Unfortunately, people don't seem to remember her, and the only person who does know her claims that she's his imaginary friend.

Malachi is not an ideal priest. At least, that's according to his superiors in the Progressive Reform Roman Catholic Church, who are already fairly tolerant. He finds the happily married couples who make up most of his congregation rather boring - he'd much rather be eating chocolate, hanging out with his friend Guiseppe (a cheerful and mild-mannered hitman), or better yet dispelling demons from the mortal realm. Malachi thinks this is best done by yelling Greek and Latin at them; Guiseppe tends to find that guns generally do the job a lot better. Unbeknownest to either of them, Malachi's deacon Balial, who is by all appearances a very cute and helpful individual, is actually a high-ranking demon seeking to corrupt the world through Malachi's unpriestliness. Or at least Balial hopes he is. This deep cover lark is harder than it looks.

The story begins in 81BC. Rome is ruled by the dictator Sulla, who has initiated period of proscription, enabling the murder of his enemies. Famous assassins take advantage of the situation, but none are perhaps as mysterious as the masked Feles. Amidst the slaughter the Romans still go about their daily lives, including the young man Quintus, who dreams of becoming something more than human...