Ghost in Trouble by Carolyn G. Hart

When Bailey Ruth Raeburn passed over into the great beyond, she was delighted to discover her sleuthing days would last an eternity. Joining Heaven's Department of Good Intentions, she uses her unique advantages as a ghost--sometimes you see her, sometimes you don't--to help those in need and ensure the wicked get their just deserts.

However, on this latest mission, Bailey Ruth finds it more difficult than ever to keep up with her boss Wiggins's rules for good spirit deportment. Not only is the woman she is supposed to save determined to thwart Bailey Ruth's good intentions at every turn, she just so happens to be one of Bailey Ruth's oldest enemies. Not that that should matter to one of Heaven's best and brightest emissaries, but still, there is only so much a person can put up with--living or dead.

But solving Bailey Ruth's toughest case yet means managing a recalcitrant charge, a fraudulent medium, a mother's heartbreak, old passions and new, and a telltale rawhide dog bone. Heaven help her!