In Tony Hillerman's The Shape Shifter, a lot is riding on a little mysterious carpet. Not any old welcome mat, but a precious Navajo tale-teller rug, full of portents, interwoven with bits of bark and feathers. Supposed to have been burned in a fire years before, the priceless artifact turns up in the pages of an interiors magazine, shown on the wall of a rich man named Jason Delos. After it's spotted by Joe Leaphorn, a retired Navajo policeman, and an old colleague of his (whose car almost immediately plunges down a canyon), the story ravels through an elaborate investigation of theft and murder.