Our Man Adelaide: The Sleeping Land (Book 4):

Although the Great War is over, the world is not at peace. Off in the East, the Russian Revolution rages, and the Great Powers, including Imperial Japan, are struggling to contain the threat of Bolshevism. Meanwhile, hundreds of tons of gold have been looted from the Imperial Treasury. Whoever controls this vast wealth wins the revolution. It is in this tumultuous setting, that Adelaide DeMarcy finds herself dispatched to Japan, and then Siberia. There, she will discover something far more valuable than gold, and contend with forces that are infinitely more dangerous than mere partisans or bandits. The Sleeping Land has been awakened…