Warnings not to go to Scotland can't stop Nancy Drew from setting out on a thrill-packed mystery adventure.

Undaunted by the vicious threats, the attractive young detective - with her father and her two close friends - goes to visit her great-grandmother at an imposing estate in the Scottish Highlands, and to solve the mystery of a missing family heirloom.

And there is another mystery to be solved: the fate of flocks of stolen sheep.

Baffling clues challenge Nancy's powers of deduction: a note written in the ancient Gaelic language, a deserted houseboat on Loch Lomond, a sinister red-bearded stranger in Edinburgh, eerie whistling noises in the Highlands. Startling discoveries in an old castle and in the ruins of a prehistoric fortress, on a rugged mountain slope and in a secluded glen, lead Nancy closer to finding solutions to both mysteries.

Wearing a time-honored tartan, Nancy climbs the mountain of Ben Nevis in the dark of night and plays a tune of historic heroism on the bagpipes -all part of her daring plan to trap the sheep thieves and to recover the valuable heirloom.