After Mirren Sutherland finds a priceless antique book in her great aunt's attic, she is contacted by Jamie McPherson, who is hopeful she might be able to find another one - a book lost in his own house. He doesn't even know the name of it, only that it is so valuable it could potentially save the entire estate from ruin, and time is running out.

On arriving at Jamie's vast crumbling home in the highlands of Scotland (on the family train, no less), Mirren meets rival bookseller Theo Palliser, whose motives are not remotely honourable; and sets out on the quest.

Jamie's grandfather was a book collector, a philanthropist, a hoarder and a great lover of puzzles and treasure hunts - as the snow falls in the highlands, cutting off the outside world, the three of them, plus Maggie, the estate manager, do their best to uncover the last hope of the MacPherson clan before the year ends: following clues, discovering the secrets of the house and forming and breaking alliances in a race against time and the weather.

Caught between devastatingly attractive and immoral Theo, and the distracted and worried Jamie, will Mirren find the book ... and lose her heart?