Whilst holidaying on the west coast of Scotland, Tolefree lets his friend Farrar take him out in a small chartered boat. When a storm hits, however, Farrar's seamanship proves less than equal to the task and the pair find themselves stranded on Eilean Rona, a lonely Hebridean island whose sole population is made up of Gregg, laird of the isle, his wife and son and their retainers. Initially, Gregg seems the consummate host, but when Farrar mentions Strachan, a friend of his who lived nearby and may have visited Eilean Rona, things take a sinister turn. What has happened to Strachan? And why are the Greggs and their entourage so secretive about the missing man's fate?