A retired Glasgow grocer on a walking holiday finds a Russian princess imprisoned in a Scottish country house and calls in a gang of slum boys to help. Buchan wrote it in 1922 as a comedy and it is the warmest thing he did; Dickson McCunn is the only middle-aged shopkeeper in thriller fiction who gets to be the hero. Fifty-four plates of coastal weather by William McTaggart and Alfred Sisley give the book the sea light and shifting skies its Scottish journey needs.