[1] Based on a story which the composer found in the journal Den svenska Mercurius (1759), the opera features several historical characters (Bure, Skytte, Queen Kristina), and is set in the university city of Uppsala just before the end of the Thirty Years' War in which Sweden became a major European power.
The war increased people's worries about the end of the world and two academics claim to have calculated when Doomsday will take place.
Lars gets arrested for threatening his tormentors with Johan Papegoja's pistol and is arraigned in front of a university tribunal, which could result in him being expelled.
With Lars afraid for his future and marriage to Elin, army captain Lennart Sporre convinces Klas to let Elin marry Lars, in return for upsetting the wager, which he does by setting fire to Wolimhaus' dog kennel (this invalidates the terms of the wager as the fire devalues the latter's effects) under cover of a thunderstorm.
Sporre and the noble students sing a serenade to Görvel and city musicians assemble in the castle tower to welcome the queen.