Grace and Mercy are very different women, but are both caught up in the war between Germany and France. When Grace is hit by a loose shell, Mercy seizes the chance to escape her past as a fallen woman and convict by assuming Grace's identity and travelling to England.
Three attempts on Russian General Trebass's his life have failed, but the Czar is determined to keep him alive. The Czar assigns the redoubtable, French detective reporter, Rouletabille to the case. It quickly becomes apparent that one of the General's own retinue is in league with the assassins...
A new tenseness seemed to have crept into the situation. The conversation, never without its emotional tendencies, at once changed its character. Philippa, cold and reserved, with a threat lurking all the time in her tone and manner, became its guiding spirit.