In the midst of World War II, English musician Norah Chambers places her eight-year-old daughter, Sally, on a ship leaving Singapore, desperate to keep her safe from the Japanese army. Sister Nesta James, a Welsh Australian nurse, has enlisted to tend to Allied troops. But as Singapore falls to the Japanese, she joins the terrified cargo of people, including the heartbroken Norah, crammed aboard the Vyner Brooke merchant ship. Only two days later, they are bombarded from the air off the coast of Indonesia. After surviving a brutal 24 hours in the sea, Norah and Nesta are captured by the Japanese and held in one of their notorious POW camps. These sisters in arms fight side by side every day, discovering in themselves and each other extraordinary reserves of courage, resourcefulness and determination.