In Haddam's 15th entry in her entertaining Gregor Demarkian series (Deadly Beloved, etc.), Bennis Hannaford discovers the murdered body of debutante heiress Kayla Anson during a Halloween visit to the Anson estate in a posh area of Connecticut. Bennis summons her lover, Gregor, retired head of the FBI's Behavioral Science Unit, from Philadelphia to help the local police. These logistics out of the way, Haddam settles into another clever plot-driven village cozy. Two more people are murdered: publicity-hungry Zara Anne Moss, who said she saw the killer, and Margaret Anson, Kayla's vengeful, money-hungry mother. Gregor studies area maps and interviews locals to separate clues from elaborate red herrings: a telephone pole knocked over, a stolen Jeep smashed in the Fairchild Family Cemetery and a skeleton from a nearby museum left on the caretakers' porch. Haddam excels at showing the chilling gulf between the arrogant wealthy and the climbers desperate to join them. One of her most complex characters is penniless divorc e Sally Martindale. Humiliated by her bookkeeping job at the exclusive Swamp Tree Country Club, Sally embezzles from members' accounts, foolishly hoping that a gambling win will restore her status among club members. In an anomalous subplot, Bennis is stricken with pneumonia and Gregor insists that she stop smoking. Haddam's well-meaning message about the perils of tobacco seems shoehorned into an otherwise smoothly running mystery marked by lively characters, good descriptions and enough misdirection to keep a reader's interest high. (Feb.) FYI: Jane Haddam is the pseudonym of Oriana Papazoglou.