Still struggling to adapt to the rigors of Parkerville, Calif. (``Gateway to the High Country'')--her switch from academic research to hands-on plant pathology; her oil-and-vinegar romance with U.C. Extension botanist Sam Cooper; all that sunshine, all those Republicans--M.I.T. transplant Claire Sharples is restless even before she stumbles over the body of Jonathan Levine, an L.A. Free Press reporter drowned in an irrigation canal with a strange yellow flower from hours away stuck in his buttonhole. Parkerville police chief Tom Martelli belittles Claire's curiosity at his peril: She digs into the story on pesticide abuse Jonathan had been following, links his demise to the deaths of two Mexican workers also found in watery graves, and leaves Sam in a snit (after returning from a trip to L.A. to find his car parked outside his ``friend'' Linda Nelson's house at dawn) for lodgings in Jonathan's seedy motel room. Before she's through, Claire will have peered so closely at every man in the case--imperious grape grower Bert Yankovich; his kid brother Emil, a stuttering liberal in love with Claire; pertinacious walnut grower Wayne Harris; even Jeff Green, her knockout blind date down in L.A.--that you'll wonder if she can ever think about a man again without a shudder. As in The Bulrush Murders (1991), Rothenberg is knowing and exact about how lovers and other people fight, and her tale is twistier than mile-high blacktop.