Marshall is a wealthy industrialist, a stubborn and determined self-made man. When he eventually learns the truth, he sets out in pursuit by aeroplane and hired car. Catching up with the puffer, he puts Pusey on board to ensure the cargo is transferred to another boat. But his underling is no match for the captain; he ends up in jail on a charge of poaching. Marshall realizes that he will have to handle the matter personally. After another costly chase, he boards the boat himself to spur the cargo transfer. However, the route and timing of the voyage are governed by MacTaggart, tidal variations and local community priorities.