Captain Holden's new job as the keeper of a lightship is exciting yet dangerous. He and his crew must remain at sea during bad weather conditions to direct passing ships away from the treacherous coast. Sarah, the captain's young daughter, proposes the idea that the family join the captain at sea. Though he is reluctant to bring his family aboard, his wife convinces him to agree to the arrangement. For a number of years, the family and crew make the lightship their home. After a gigantic storm destroys the lightship, however, their tour of duty is brought to an abrupt end.