In the midst of the fighting, two Russian soldiers seek refuge in the crypt of a German church. There, clutched in the hands of a skeleton priest, they find The Shepherd - a priceless icon thought to have been destroyed long ago. When news of its discovery reaches Moscow, Stalin calls upon his most trusted investigator, Inspector Pekkala, once a favorite of the tsar and known to all of Russia as The Emerald Eye.

A soldier returns from the front line of battle to report that Pekkala's charred body has been found at the site of an ambush. But Stalin refuses to believe that the indomitable Pekkala is dead. On Stalin's orders, Pekkala's assistant, Kirov, travels deep into the forests of Western Russia, following a trail of clues to a wilderness where partisans wage a brutal campaign against the Nazi invaders. Unknown to Kirov, he is being led into a trap.

September 1939: The Second World War has begun. Even as the fighting rages in Poland, Stalin's long-time obsession with the missing treasure of Tsar Nicholas II is rekindled. An informant claims to know the whereabouts of the man entrusted by the Tsar with hiding his gold. As the news of the informant reaches Stalin, however, the man is knifed to death. Stalin summons Pekkala to the Kremlin and orders him to solve the murder. To accomplish his mission, he must return to Borodok, the notorious Gulag where he himself spent many years as a prisoner.

As Hitler's forces smash into Soviet territory, a lone German scout plane is forced down. Contained in a briefcase within is a seemingly inconsequential painting of a red moth. Military Intelligence dismisses the picture as insignificant, but Stalin suspects a German plot. He summons his old adversary, Inspector Pekkala - the Finn who was Tsar Nicholas II's personal detective - to discover the real significance of this strange cargo. As the storm gathers, Pekkala and his assistant from the Bureau of Special Operations find themselves on the track of the most formidable art thieves in history.

Sommer 1941: Hitlers Truppen marschieren scheinbar unaufhaltsam voran, über Russland wird ein deutsches Aufklärungsflugzeug abgeschossen. Darin findet sich ein Gemälde, das auf den ersten Blick einen großen Nachtfalter darstellt. Doch Inspektor Pekkala erkennt in dem Gemälde einen getarnten Grundriss der Zarenresidenz im ehemaligen St. Petersburg. Daraufhin argwöhnt Stalin, dass es die Deutschen auf das legendäre Bernsteinzimmer abgesehen haben, und schickt Pekkala in die belagerte Stadt.