HMS Guernsey is a policewoman of the sea. The laws she enforces define the dos and don'ts of fishing. Her beat is three-quarter-million square miles of coastal water. The trawler skippers she orders to accompany her to the nearest port appear before magistrates with the power to fine up to £50,000, and confiscate the catch and the nets - crippling blows to the master of the Jose Caesareo and the master of the Candida Viera , whose stories are the subject of this film. Both were caught with their nets down inside Britain's 200-mile limit. Both faced bankruptcy and ruin. But for the men who sail the Fishery Protection Vessels it was a success, an essential demonstration that valuable fish stocks must be protected and conserved, so that when finally the argument over Britain's fishing limits is settled, there will at least be something within those limits left to catch.