The narrative unfolds in Connecticut and New York during the mid-1960s. Eleven-year-old Claudia Kincaid, weary of her daily duties, devises an adventure: she plans to run away and live in New York's Metropolitan Museum of Art. Her scheme includes her nine-year-old brother, Jamie, who is frugal yet shares her adventurous spirit. The siblings both adore the thrill of adventure and make a perfect pair, with Claudia being cautious about everything except finances, while Jamie is reckless in all matters except money. Together, they form a dynamic duo that first manages to infiltrate the museum and then embarks on a quest to uncover the mystery of Angel, a two-foot statue believed to be crafted by Michelangelo. Their quest to verify the statue's authenticity as a piece by the renowned Renaissance artist leads them to significant revelations about themselves, each other, and the essence of being extraordinary.

Konigsburg effectively utilizes her limited cast of characters by employing a narrative structure that operates on multiple levels simultaneously. The story is framed by the narrative that Mrs. Frankweiler sends to her lawyer, Saxonberg. Through this correspondence from a wealthy, eccentric older woman to her legal advisor, Mrs. Frankweiler's character is developed. She comes to realize that loneliness is a steep cost of her eccentricity, and Saxonberg's stubborn righteousness. Throughout the narrative, she playfully criticizes his extreme propriety, revealing her feelings for him and indicating that the story has concluded, as she can now recount it to Saxonberg. Therefore, even though Claudia and Jamie's future is uncertain, it is clear that nothing too dire awaits them. Mrs. Frankweiler's tone suggests a positive outcome.

By selecting Mrs. Frankweiler as the narrator, Konigsburg achieves a balance between the objectivity of a third-person narrator and the closeness of a first-person perspective. Mrs. Frankweiler can provide an objective viewpoint since she only encounters Claudia and Jamie at the story's conclusion. However, she also delivers the subjective details typical of a first-person narration because she insists on a full account from Claudia and Jamie as compensation for giving them a ride home.

Claudia and Jamie's adventure is unique because it lacks the typical elements of a battle between good and evil, any form of violence, or traditional suspense. Despite this, some parents might worry about their actions, which include running away, taking coins from a museum fountain, trespassing, and causing distress to their parents. It's crucial for young readers to understand that this story is a childhood fantasy rather than a realistic portrayal. Many parts of the story are highly unrealistic: the children spend about a week living in the Metropolitan Museum, exploring exhibits at night, and making noise in the restaurant fountain without triggering alarms or alerting security. Additionally, Claudia's plans seem to succeed too easily; no one questions a sixth-grade girl and a third-grade boy wandering alone in New York City. They even manage to rent a post office box at Grand Central Station without a permanent address or adult supervision. Although some of their activities are questionable, the story is clearly meant for enjoyment, and it's unlikely anyone would take it as anything more than a playful adventure.

The 1973 film adaptation of From the Mixed-Up Files of Mrs. Basil E. Frankweiler shares the same title as the book. It was later re-released under the name The Hideaways. Directed by Fielder Look, the movie features Sally Prager, Johnny Doran, and Ingrid Bergman, who plays the role of Mrs. Frankweiler.

Jones, L. T. "Profile: Elaine Konigsburg." Language Arts 63 (1986): 177-184. This article offers both a biographical and character analysis.

Kirkpatrick, D. L., ed. Twentieth-Century Children's Writers. New York: St. Martin's Press, 1983. This book provides an overview of Konigsburg's life, a list of her works, and a concise critical evaluation.

Konigsburg, David K. "Elaine L. Konigsburg." Horn Book 44 (August 1968): 396-398. This piece provides biographical information on Konigsburg.

Konigsburg, E. L. "Acceptance of Newbery Award." Horn Book 44 (August 1968): 391-395. In her acceptance speech, Konigsburg shares her thoughts on writing for young audiences.