To give you a quick idea of what Monninger's new hero, Mather Edson, is like: When he ventures forth from the Plaza, where he's staying with Nancy, his Airedale, he's not above keeping her on a harness and posing as a blind man. Mather's been lured down from his hermit's life in New Hampshire by socialite Peggy Ramsey, his old Peace Corps friend, who insists that only he is expert and discreet enough to round up her estranged husband, Ollie Potter, who dropped out of a cushy law firm to work in a housing project and then dropped out of the project together with their three-year-old daughter, Hazel, now the subject of a million-dollar ransom note. Mather has a flip, agreeable line of patter that combines back-to-nature minimalism, wrestling, a healthy contempt for Peggy's family and everything they stand for, and a prim revulsion from the kinky videotapes and steroid abusers the case will expose him to before he's done. You can pretty much fill in the rest of the laid-back story yourself: This is not one of those nasty kidnappings in which the victim gets shipped home one tiny finger at a time. If it's the business of a debut mystery to establish a hero you'd like to spend more time with, then Monninger's seventh book (Incident at Potter's Bridge, 1992, etc.) more than fills the bill. Now let's give the man a plot he can get his teeth into.