As the English Civil War rages in 1642, a young Irish girl called Sorcha O'Neill is separated from her family at the siege of Carrickmain Castle. She fears the same fate as many of her compatriots: death at the hands of the English. Salvation arrives in the unlikely form of Lieutenant Robert Hammond, who names the girl Dublin, the only word the wild, terrified girl will speak in English. Leading her from the battle to safety, Hammond decides to take Dublin to his family on the Isle of Wight for refuge. As the two form an unlikely bond, the only certainty is that their lives will never be the same again.