Before taking up her eagerly anticipated promotion to Sister Victoria Ward, St Martha's Hospital, London, Staff Nurse Charlotte Anthony spends four weeks in a little hospital on the isolated, far-northern Isle of Thessa. Charlotte quickly learns that instead of the quiet cottage hospital she expected, Thessa General, though tiny, is ultra-modern and staffed and equipped to deal with the variety of medical and surgical emergencies that come in from Thessa, her sister islands, the world's fishing fleets and the oil rigs. The patients come in by trawler, tanker, merchantman, lifeboat, helicopter, ambulance ; at all hours, in all seasons, in storm and in calm. Charlotte encounters new professional problems, new friends - seismologist Rod Hardin.