The year is 1904. It is four years since their joint effort prevented a horrible attack in Paris. Robert LePage is in Berlin working undercover to track down a group of German soldiers wanting to start another war. Patrick Dupuy is in London setting up a cover story to help him monitor British government officials. They must leave their cases to track down those behind the plot to assassinate the Russian Czar, a mission which will take them to St. Petersburg and make them need again the services of a woman neither can really trust.