When Sander Weir leaves everything to Morag, the girl he and his wife raised as their own daughter, his brother Lawrence feels that he has been cheated of his inheritance. As Morag's real father, who abandoned her as a child, he makes it clear that he should have control of her new-found wealth, but with the support and encouragement of Cal, skipper of one of the small Clyde 'puffers' (cargo boats) Morag now owns, and Aidan, a young lawyer, Morag finds the courage to defy Lawrence and run her own affairs...