Detective Lindsay Boxer is jogging along a beautiful San Francisco street as a fiery explosion rips through the neighbourhood. A townhouse is engulfed by flames and when Lindsay plunges inside to search for survivors, she finds three people deadh and a sinister note signed August Spies. Soon a wave of violent incidents, all with links to political terrorism, sweeps through the city. Lindsay asks her three friends, the Women's Murder Club, to help her figure out who is committing these murders - and why they are intent on killing someone every three days. Before long, the investigation is raging furiously, especially when the killer begins to target one of the Women's Murder Club.