1912 The First World War is just around the corner. Young aviators Vladimir Slyusarenko and Lydia Zvereva, the first Russian female aviatress, are working on a reconnaissance airplane project. Their activities are supervised by the Russian military department. Riga was chosen to work on the airplane, with its factories where orders for engines and equipment can be placed, and with its airfield, which is located on the territory of the Solitude hippodrome. At the same time, Maximilian Ronge, one of the intelligence leaders of Austria-Hungary, which has its own spy network in Russia, sends three agents to Riga - Tulip, Centaur and Alda. Their task: at best, to recruit young aviators, at worst, to simply steal the drawings...