Virgil Tibbs and the Cocktail Napkin

Virgil Tibbs's second case in short-story length--another police procedural featuring the most famous black detective in fiction, the protagonist of that wonderful movie, "In the Heat of the Night" . . .All Virgil had as a clue was a cocktail napkin, but that was enough for him to out-Sherlock the Great One himself. Follow the trail with documentary detail . . .