Routine mystery-suspense set in ancient Rome (116 A.D.), jolted along with grisly atrocity details, wrangles among persecuted Christians, and a brace of companionable sleuths. Lovely young Tullia, a Roman prefect's daughter engaged to a horrid Syrian merchant, is ambushed and kidnapped in the sight of Marcus Silanus--who loves her but is a social outcast because of his choice of Philosophy as a career. So, when the praeter Quindarvis, who sponsors beast-and-Christian galas in the arena, finds a Christian medal at the kidnap-scene, a horrified Marcus (he's heard tales of gory Christian rites) begins the search for Tullia. His co-sleuth is wily old aristocrat Claudius Sixtus Julianus. And the investigation focuses on the caged Christians--an untidy, cantankerous lot, firing theological dialectic at one another while awaiting various colorful ends. (Centurion Arrius turns thumbscrews or slits throats during interrogations.) But, predictably, Marcus' anger at the Christians slowly changes to respect and admiration--as he's led by the anonymous Christian-underground mastermind (""Papa"") through a series of chases, spying, and near-fatal adventures (a brothel, a web of tombs, a blazing villa, a pride of ravenous lions, a baby-roasting ceremony). . . till the lady is rescued and the villain chomped in a leonine banquet. A workable, busy yam--flecked with I, Claudius grue.