I am a librarian. I like things to be in order. I like things to be complete, but I have been troubled for the past year. You see, Sally Draper was shown reading a book in Mad Men season four, episode five ("The Chrysanthemum and the Sword"), and I could not for the life of me figure out what that book was. The Mad Men Reading List was incomplete and, as a librarian, that troubled me to my core. I made screen captures to get an image of the illustration. I checked the promotional still from AMC's website to get an image of the cover. I pushed pixels to make the images clearer. I searched Google for hours with no luck.

I finally did what I should have done from the beginning and turned to the experts. I contacted NYPL children's materials superstar and fellow ornithologically-surnamed coworker Betsy Bird. She put the request out to children's librarians everywhere via her blog, and in a matter of minutes the mystery was solved. The Twenty-One Balloons, by William Pène Du Bois.

Mid-Manhattan Library happened to have a copy, so I went quickly downstairs to the children's fiction section for confirmation. I thumbed through the pages. It didn't take long. The illustration on page seven showing the explosion of Krakatoa matched the image from the show.

Sally's copy of the book.My copy of the book.

The Twenty-One Balloons was published in 1947 and won the Newbery Medal for excellence in American children's literature in 1948. The copy Sally is reading doesn't appear to have the Newbery award seal, so it's probably the first edition. The episode takes place in 1965, so to show Sally reading a mid-century award winning children's book is only appropriate.

What makes The Twenty-One Balloons even more appropriate is its connection to another title on the Mad Men Reading List. When du Bois finished The Twenty-One Balloons, his publisher brought to his attention the striking similarity between his book and F. Scott Fitzgerald's short story "A Diamond as Big as the Ritz." Du Bois included an Author's Note at the beginning of his book to clear the air of any perceived wrongdoings. He claimed he was not aware of the Fitzgerald story when he wrote his, and any similarities between the two were just an extraordinary coincidence. Fitzgerald's "A Diamond as Big as the Ritz" appeared in Babylon Revisited and Other Stories and was read by Sally's mother Betty in season two.

This gives fans of the show something to think about: two works of fiction that are so similar, with one clearly written for an adult audience and the other for children, and the significance of the mother reading one and the daughter reading the other two seasons later. The fact that both works were so similar was a coincidence. The fact that both works appeared in the show was not. It's the kind of details that are all but overlooked by the majority of viewers, but if you're a fan of the show, this is the kind of stuff that makes you smile.

Crowdsourcing the investigation solved the mystery of what Sally was reading almost immediately. My thanks go out to Betsy for blogging my inquiry, and to all of her readers who joined in the investigation — especially Tracy for being the first to recognize the book. Librarians truly are among the most helpful and informative individuals! I am no longer troubled by an incomplete Mad Men Reading List, and I have another title to add to the Sally Draper Reading List.

Now to wait for season five....