ACT I: Love
The action takes place in the Tyrol, during the first half of the eighteenth century. Luisa, the daughter the aging soldier Miller, is in love with Rodolfo, whom they know only as the peasant Carlo. Miller has a premonition that their relationship is doomed, and his fears are confirmed when Wurm (who also loves Luisa) informshim that Carlo is Rodolfo - the son of his employer Count Walter.
The duchess Federica, Count Walter's niece, arrives at the castle. She was once in love with Rodolfo, and now that her husband has died she has been invited by Count Walter as a suitor for his son. Wurm tells the count that his son loves Luisa Miller. This elicits a furious response from the count, who vows to bring their reltionship to an end.
Rodolfo tells Federica that he is in love with Luisa, and then reveals his true identity to Luisa and her father. Unable to dissuade his son, the count imprisons the Millers, thus provoking Rodolfo into threatening to reveal how his father obtained his title by killing his predecessor. Luisa and her father are then released.
ACT II: Intrigue
Luisa is desperate to save her father, and so writes a letter falsely claiming that her pursuit of Rodolfo was motivated solely by his rank and estates. She also convinces Federica that she is no threat to her union with Rodolfo. When the count and Wurm show Rodolfo Luisa's letter, he agrees to marry Federica.
ACT III: Poison
Luisa has decided to take her own life, but is talked out of it by her father. Rodolfo enters moments before his wedding and asks Luisa if she wrote the letter. When she confirms it, Rodolfo drinks some poisoned water and gives some to Luisa before telling her that they are both dying. Luisa then confesses her love for Rodolfo, who manages to kill Wurm before falling dead himself.