It can be tough being an undercover revenue officer, but DJ Smith has a little help from her trained sniffer cat Gorgonzola, a moth-eaten Persian with gourmet tastes. This first investigation finds DJ and Gorgonzola on the trail of a heroin smuggling ring operating in and around Edinburgh. Along the way they make the acquaintance of Felicity Lannelle, an unscrupulous gastronome and Hiram J. Spinks, an American golfing fanatic. As the duo near the climax on the lonely Isle of May it appears that a real cat and mouse game has just begun...