Readers seduced by the first two books in JoAnn Ross's Callahan Brothers trilogy (Blue Bayou; River Road) will be equally charmed by Magnolia Moon. When charismatic Nate Callahan, the mayor of Blue Bayou, La., tracks down Los Angeles homicide detective Regan Hart to deliver a journal and a tidy sum in stock certificates left to her by her birth mother, Nate is surprised by Regan's reaction. She isn't interested in her inheritance, but she's stunned to learn that she's adopted. To uncover the truth about her past, Regan returns to Blue Bayou, where she delves into the mystery behind her mother's death and becomes intimately involved with Nate. Meanwhile, Nate receives temporary custody of an abused 12-year-old runaway. Ross focuses heavily on the topic of domestic violence, and her frequent moralizing may put off some readers. Others, however, will be sufficiently beguiled by the book's Southern ambiance and pleasing, if predictable, romance.