Father Francesco Rucelli awakens in a Florence hospital after the explosion that injured him and killed his twin, Dominican monk Piero. Piero, custodian of the vast Rucelli fortune, had become increasingly erratic since finding a relic of fellow Dominican Girolamo Savonarola, a fanatical monk who subjected Florence to a "bonfire of the vanities" in 1496. Piero may be connected to an outbreak of arson and violence eerily similar to tragedies during Savonarola's reign.

Inspector Stefano Berti, head of Florence's major crime unit, wants Father Francesco to shed some light on the crimes,...