Huntingtower by John Buchan
Dickson McCunn, a respectable, newly retired grocer of romantic heart, plans a modest walking holiday in the hills of south-west Scotland. He meets a young English poet and, contrary to his better sense, finds himself in the thick of a plot involving the kidnapping of a Russian princess, who is held prisoner in the rambling mansion, Huntingtower. This modern fairy-tale is also a gripping adventure story, and in it Buchan introduces some of his best-loved characters, including the Gorbals Die-Hards, who reappear in later novels. He also paints a remarkable picture of a man rejuvenated by joining much younger comrades in a challenging and often dangerous fight against tyranny and fear.