A misty Irish mystery has for its background the Mayo coastline and the legends surrounding the island of Inishmanann and the sea god Manannan. The story tells of young Michael Farrel's quest for his long lost father who had gone off to the island in search of the riches the legend promised. It is a well paced unfolding of plot with the special atmosphere that gives it its meaning. When rumors come to light of Mr. Farrel's possible survival, young Michael who has been keeping the farm with his mother, determines to set out in a small boat with his friend Joe. For their helpers they chose a questionable pair, Pat and Matt, and the voyage to the fog shrouded island leads them not only to Michael's father but to Pat and Matt's lair of thieves where justice is done and Mannanan makes good his promise.