The year is 1760: it is the time of the Seven Years' War and the advancing Russian army has taken captive 100 underage Prussian cadets. The kids are mishandled by the raping and pillaging Russians, but with the help of a Rittmeister now in the service of the Tsar, they succeed in getting away. They hole up in a deserted fort and eventually sally forward to take back their military academy from the bloodthirsty, pillaging Cossacks.

The guests at Count Otto von Trepow's East Prussian estate Gross-Ehrenfeld are Lord and Lady Ruthven, Mr Hendriks with his wife and foster-daughter Mariska, a gypsy they adopted years ago, Kundry, the fiancée of Otto's son Bernhard, and Count Stanislaus Larinski, who claims to be a Polish revolutionary wanted by the Russian government. A boating trip is organized but ends when the motor breaks down. While waiting for it to be repaired, the guests go to an inn run by Andreas and his daughter Käthe. Hendriks goes for a walk, sees the boat come back and that a man with a bent back leaves it. He notices that Kundry is afraid of Bernhard.