Emily Taylor, a young headmistress from Yorkshire, first sails aboard the RMS 'Lusitania' in 1910 whilst travelling to attend a family wedding on Long Island in America. During that first voyage, she makes a number of acquaintances, all with secrets in their pasts: Amelia Davenport, a flamboyant elderly widow with a salacious history, who is emigrating to America with her son and his family; Sam Jackson, a tough New York Police Inspector, driven by a personal vendetta; Christian Verholt, the heir to a wealthy banking dynasty whose double life includes a mysterious partner; and Niall Branigan, the charming Irish doctor whose twinkling emerald eyes mask hidden family secrets. But as the threat of the First World War looms, it is not only Emily's life that changes dramatically as a consequence of these encounters, but also the lives of those close to her back in England.