Of Love and Evil is the second instalment in Anne Rice's "Songs of the Seraphim" series, about the adventures of time-travelling Catholic sleuth Toby O'Dare. (Imagine Quantum Leap, but with added Christian proselytising.)
In the first book, an angel transported our hero to medieval Norwich, but this time around his mission is rather more glamorous, and involves a journey to 15th-century Rome to investigate the poisoning of a prominent nobleman. Unfortunately, Rice's descriptions of Renaissance Italy fail to convince, and her tendency to break into strained, God-praising rhapsodies is off-putting. Indeed, the book steams with such hot and fervid expressions of faith that you feel like throwing a bucket of cold water over it.