Fresh from the momentous experiences of his maiden voyage, merchant seaman James Dunbar is back in his native Suffolk. Struggling to recapture the intensity of that Mexican adventure, when he discovered his own distinctive artistic spirit, he seeks inspiration in Julia Ravenham, an enigmatic beautiful aesthete eager to nurture his young talent. He falls in love, but the emotional and artistic approval of bohemian London cannot quell the call of the sea. It is his vocation, but also his destiny. In securing a berth aboard Fort Mackinac, a sailing ship bound for Australia, Dunbar strives to build the character essential for a successful career. Even after four years of hunger, humiliation, danger and remorseless physical labour wreaking havoc upon his mental state - but seeing his paintings of crew life acclaimed - Dunbar's sense of purpose remains undimmed. Yet with the outbreak of naval operations in the First World War, his artistic past returns in haunting fashion, provoking a desperate confrontation amid the wilds of the South Atlantic Ocean...