The White Deer concerns faith in love. Love depends upon the will of lovers to believe in each other despite all obstacles. Though the story is playful, fast-paced, funny, at times satirical and at times absurd, the theme is serious, as are the obstacles thrown up before the lovers. Secrets of the past and fears of the future, prejudices and the lack of imagination, accident and sorcery all threaten love's survival.

Loosely adhering to fairy tale conventions, Thurber invites the reader into an imaginary world where an enchanted white deer, cornered in a magic forest, is suddenly transformed into a beautiful princess without a name. She sets King Clode's three sons—Thag, Gallow, and Jorn—tasks to perform to decide whom she will marry. The tasks she sets for Thag and Gallow are perilous but she chooses an easy task for Jorn, her favorite. In the meantime, the king's advisors discover that in every previous case in which a transformed deer cannot remember her name, she is truly a deer and returns to her original shape when love fails her thrice. When all three princes succeed and return simultaneously, however, they must decide whether to accept her, despite the discouraging precedent. Although their quests test the princes in various ways, the final test of their faith in love rests on their decision to accept or reject the princess.

The single most important quality that fosters faithful love in this story is imagination. Jorn, as a poet, can succeed where his brothers fail because the good he imagines rules over the supposed facts. As a master of words, Jorn is also aware of his power to shape reality to his desires. Though Thurber presents this power in a fairy tale setting, he knows it to be a true power, limited as it may be in real life. Of all the shapes and meanings people can give to the world, the best are those that foster love.