April 1916. In London, Eva Gore-Booth is shocked to read a newspaper report that her sister Constance lies dead on a Dublin street. She rushes to Westminster and British Army headquarters and discovers her sister is alive, but condemned to death. Meanwhile, in Kilmainham Gaol Constance hears the firing squads killing her closest friends as she awaits her fate. Sisters against the Empire tells the remarkable story of one of Ireland's most famous families at the time of the Easter Rising and its aftermath. Countess Constance Markievicz, one of the leaders of the Rising, is arrested by the British but, due to her gender, her death sentence is commuted to life imprisonment. Her sister Eva, dismayed at the atmosphere of fear in Dublin, fears that solitary confinement will drive her sister insane. The Gore-Booth family are divided between conflicting loyalties. Sir Josslyn Gore-Booth begins to sorts out his sister's finances and writes endless letters to uncover the truth behind the rumours Constance killed a policeman on St. Stephen's Green. Eva returns to London where she attends the trail of Sir Roger Casement and campaigns against his execution.
The next twelve months will stretch Eva's physical and mental powers to the limit. She becomes Constance's ally and closest confidant, her go-between and secretary and connection with the Gore-Booth family. Constance struggles against the attempts of the prison authorities to crush her revolutionary spirit. The prison rations weaken her health and she suffers periods of illness and desperation. During her dark season of the soul she finds an outlet by producing a remarkable series of drawings and sketches in her prison Journals, reproduced here for the first time. Sisters against the Empire draws on new sources to show how "two girls, both beautiful, one a gazelle" defied the might of an empire at war. This is history with the attention to detail and vivid characterization, told with the intensity of a novel.