The novelist Piers Paul Read wants us to know that the real Vitellio Scarpia, an 18th century Sicilian soldier for the Papal States, was not “sadistic,” as he is apparently shown to be in a play by one Victorien Sardou. Rather, in Read’s book “Scarpia” (2015), he is humane, dutiful, respectful of Catholicism—as well as highly imperfect. But not a cur.

In addition, Scarpia is anti-Jacobin, living when revolutionary France does bloody-minded harm to Italy. Not surprisingly for a Read novel, the subject of salvation crops up. The Arletty of Rome, the woman who sleeps with French Jacobins—Scarpia’s estranged wife, Paola—is the only character in the book who after repentance reaches a deep Christian devotion. One person, maybe more, has considered this Catholic propaganda. It is nothing of the sort. The conversion is one occurrence among many, taking place, remember, in Catholic Italy. And this book—riveting if not always satisfactorily edited—is not preachy at all.