Treason at Lisson Grove by Anne Perry

Treason at Lisson Grove: A Charlotte and Thomas Pitt Novel - Special Branch officer Thomas Pitt chases a known terrorist to France.  He and his partner are keeping watch over a house that houses leaders of an international plot to abolish all monarchies.  Meanwhile, Victor Narraway, Special Branch’s leader has been accused of embezzlement and has been removed from office.  Pitt’s wife, Charlotte and Victor, embark on their own chase to Ireland to find the root of the plot against Victor.