Roy, a reader new to the Dismas Hardy series, is oddly unemotional in his rendition of Lescroart's 20th book featuring genial San Francisco defense attorney Hardy and his pals. The mystery revolves around the death of Grant Wagner, the wealthy owner of a plumbing-supply company, who was killed using an uncommon poison, aconite. Circumstantial evidence points to his bookkeeper and former lover, Abby Jarvis. Though Hardy has promised his wife to stay clear of trials involving murder, he feels compelled to help Abby, a client from long ago, so he hires private eye Wyatt Hunt to snoop around Wagner's sons and daughters and gather info on two other murders that occurred after Abby's arrest. A connection could set her free. Much of the popularity of these novels comes from the personalities and abiding friendship of easygoing Hardy, quirky district attorney Wes Farrell, and humane, impatient homicide detective Abe Glitsky. All of that is present, though Roy doesn't quite nail the distinct charm of each character, while the genuinely funny banter among them also falls flat. The novel has well-developed characters, cleanly detailed San Francisco locales, and a sturdy whodunit plot, but it's a bit shy on suspense and thrills, a point underlined by Roy's unruffled recitation. An Atria hardcover. (Feb.)