B is for Burglar (Kinsey Millhone Mysteries) by Sue Grafton

Finding wealthy Elaine Boldt seems like a quickie case to Kinsey Millhone. The flashy widow was last seen wearing a $12,000 lynx coat, leaving her condo in Santa Teresa for her condo in Boca Raton. But somewhere in between, she vanished. Kinsey's case goes from puzzling to sinister when a house is torched, an apartment is burgled of worthless papers, the lynx coat comes back without Elaine, and her bridge partner is found dead. Soon Kinsey's clues begin to form a capital M -- not for missing, but for murder: and plenty of it. Winner of the 1985 Private Eye Writers of America Shamus Award and the 1985 Anthony Award for Best Novel.