Roman tells about the first victory of the Russian army in war 1812 year, when the corps of general Витгенштейна, considerably yielding in a quantity, stopped to two French corps the way on Saint Petersburg in a sanguinary battle near a village Клястицы. His protagonist is a military intelligence officer captain-artilleryman Ярцев, working in the rear of enemy under the guise of Italian quartermaster Донадони, managed to procure the most secret plans French marshal Удино. By means of the well-run connection they were immediately passed in the staff of the Russian corps and helped to overcome an insidious enemy. For these successful actions an emperor Alexander I named Витгенштейна the rescuer of hail of Петрова and only from all participants of war with Napoleon appropriated the high rank of general from a cavalry.