Edinburgh, and the island of Islay, world famous for its Scotch whisky distilleries, is the setting of the third assignment for DJ Smith, agent for HM Revenue & Customs, and her "sniffer" cat, Gorgonzola.

The girlfriend of Louis Moran has arrived in Scotland and is staying as the guest of Sir Thomas Cameron Blaik, wealthy and respected businessman and owner of Srón Dubh distillery.

HMRC are convinced that Moran, a ruthless international drug baron, will join her there, and that as well as finalising another drugs operation, Sir Thomas's whisky business may well be a target. DJ Smith is sent in undercover role as butler to Sir Thomas. Accompanying her is her "sniffer" cat Gorgonzola whose sensitive nose detects something much more sinister than drugs.

With millions of pounds worth of whisky and drugs at stake, anyone who stands in Moran's way will die, anyone who even rouses the slightest suspicion - and DJ Smith does exactly that. Others who have threatened his multi-million pound master plan have already been eliminated, and one more makes no difference. Can DJ remain undetected long enough to identify Moran and make her escape?

A dramatic endgame is played out in darkness on the Firth of Forth with a backdrop of the twinkling lights of Edinburgh.