The Russian Cage

I always include major spoilers (hidden), to help with my memory  issues. Read them at your peril! 

Lizbeth Rose travels to the Holy Russian Empire to free Eli from jail. Whilst there Felix arranges for her to ”save” the tsarina from an assassin, which gets her into the palace to visit the tsarina and get permission to visit Eli . She poses as a cleaner in the palace, and then kills the tsar's uncle, inadvertently sparking off a coup attempt by the dead uncle's family