The main idea of "The Lady or the Tiger?" surrounds the choice presented by Frank Stockton. His story examines the motives of the human heart, when propelled by the conflicting emotions of desire and hatred, jealousy and grief. The key figure, the daughter of the semi-barbaric king, is a hot-blooded princess with "a soul as fervent and imperious as his own." Ultimately, her handsome young lover's fate rests in her hands alone; she has the power to direct him toward either door, to send him to a gruesome fate or reward him with a blushing bride that she just happens to loathe.
The story's uncertain ending poses the question to the reader:
"The question of her decision is one not to be lightly considered, and it is not for me to presume to set myself up as the one person able to answer it. And so I leave it with all of you: Which came out of the opened door - the lady, or the tiger?"
Stockton's central idea within "The Lady or the Tiger?" is to examine the human heart and the princess's compelling decision, ultimately leaving the outcome for the reader to decide.