The book opens with Colin Dare aboard the old whaler Gull in the Behring Sea, where he eagerly joins a small boat crew to witness the harpooning of a gray whale. Despite the dangers of the hunt and the close brush with the giant leviathan, Colin's courage wins the admiration of old Hank, the seasoned gunner. The narrative then shifts to the Pribilof Islands, where Colin is shipwrecked and subsequently finds a safe haven on St. Paul Island.
Here, he explores the vast seal rookeries, observing the complex social hierarchy and brutal fights of the bull seals, as well as the gentle play of the bachelors and pups. He learns about the life cycle of the fur seal and the constant threat of ruthless Japanese poachers who endanger the survival of the species. An unexpected encounter with these poachers leads to a tense midnight confrontation on the rookery, resolved by the timely intervention of a revenue cutter.
Later, Colin's journey takes him to the Columbia River, where he learns about salmon propagation and tagging from a university professor, experiencing firsthand the meticulous work of fish conservation. Finally, the narrative follows him to the waters of Santa Catalina Island, where he transitions from a spectator to an active participant in sport fishing, culminating in the triumphant landing of a hundred-pound tuna and earning a coveted blue button from the local angling club. Throughout these adventures, Colin grows from an eager, bookish boy into a knowledgeable young man whose life course is set firmly toward a career in marine science and the Bureau of Fisheries.
