Set in London and Ulster in 1914, Cat and Mouse is the gripping story of two sisters fighting for their ideals in the turbulent months before the outbreak of war.

When Sarah Becket, a militant suffragette determined to help free Mrs Pankhurst from prison, discovers that her own husband, a respected Liberal MP, is involved in a scandalous prostitution racket, she is devastated. Still weak from imprisonment herself, she takes a knife from her kitchen and goes out into London's West End, determined to protest for women's rights in the most dramatic way she can.

Across the Irish sea, her younger sister, Deborah Cavendish, is lonely and unloved. When her husband returns home to join the Ulster Volunteers and fight the government, she faces an agonizing choice - to end her affair with James Rankin, the trade union leader whom she she thinks can give her all the love her husband has denied her, or face social ostracism and the loss of her beloved son. When she reads about her sister's act of defiance, she resolves to go to her aid.

United by their cause, Sarah and Deborah combine to fight both male corruption and a German plot to foment civil war in Ireland.