During World War II, a cargo vessel (S.S. Cabinet Minister) is wrecked off a remote Scottish island group — Great Todday and Little Todday — with fifty thousand cases of whisky aboard. Due to wartime rationing, the thirsty islanders had nearly run out of the "water of life" and see this as an unexpected godsend. They manage to salvage several hundred cases before the ship sinks. But it is not all clear sailing. They must thwart the efforts of the authorities to confiscate the liquor, particularly in the shape of misguided, pompous English Home Guard Captain Paul Waggett. A cat-and-mouse battle of wits ensues.
Although the wreck and the escapades over the whisky are at the centre of the story, there is also a lot of background detail about life in the Outer Hebrides, including e.g. culture clashes between the Protestant island of Great Todday and the Roman Catholic island of Little Todday. (Mackenzie based the geography of these islands on Barra and Eriskay respectively, but in real life they are both Catholic islands). There are various sub-plots, e.g. two couples who want to get married.
Mackenzie's prose captures the various accents of the area and also includes much common Gaelic that was in use at the time. The book comes with a useful glossary of both the meaning and approximate pronunciation of the language.