What would you do if you discovered a secret message scribbled inside a library book? And what if it was a clue to a mystery you were trying to solve?

In 1963, a young library worker named Geoffrey Lapin discovered something mysterious about a favorite book detective, Nancy Drew. Library records stated that no one knew who had written the stories about her. The author's name on the books read 'Carolyn Keene.' But some people said there was no such person. The only printed fact Geoffrey could find said, 'Carolyn Keene, real name unknown.'

Then, Geoffrey found a clue-a message inside a Baltimore library book. Right next to the name Carolyn Keene, someone had penciled in another name-Mildred Wirt. Next to that, the person had written another clue: 'See American Woman, 1939-40.'

Who was Mildred Wirt? It seemed as if Geoffrey's old chum Nancy Drew was whispering in his ear. He had to solve this mystery.

Quickly, he located the book American Women. What he found there must have made him catch his breath. Someone named Mildred Wirt Benson, her married name, had written more than 130 children's books. And she'd used pseudonyms. Was Carolyn Keene one of the made-up author names  she'd used? If so, why would she hide her true identity?

What would Nancy look for next? Fingerprints! An author's writing style was like her fingerprints. She couldn't hide her style. And no one else could duplicate it exactly. If Geoffrey found Mildred's other books, he could compare them with the Nancy Drew books.

Combing through antique stores and musty bookshelves, Geoffrey said he had 'truly found a gold mine.' Every book he read by Mildred was filled with word pictures similar to those he'd read in Nancy Drew books. Secret passageways, country roads and roadsters wound their way through the books he found, just as they did in the popular series. It was as if Nancy was having adventures under the names of other characters. And Mildred had written those adventures using different author names. But why?

Only Mildred could reveal this secret. Geoffrey arranges an interview. The moment they met, he felt as if he were talking to Nancy Drew herself. As a longtime reporter for the Toledo Blade, Mildred had detecting in her blood-just as Nancy did. Like Nancy, Mildred broke molds of what people thought women should do. She was the first woman to graduate from the University of Iowa School of Journalism. In 1927, she received the first master's degree the school ever gave. Her adventurous life included becoming a pilot, a champion diver and swimmer.

After sharing these details about her life, Mildred confirmed what Geoffrey suspected. She was the original Carolyn Keene.

When Mildred was a college student, she'd heard of a writing job with the Edward Stratemeyer publishing syndicate.

Stratemeyer had decided to form a sort of factory to write children's books. His idea was to hire writers to 'ghostwrite' books under made-up names. This way, he could hire various writers to author a series from his own story ideas. He would be able to publish many books quickly. An if one writer quit, it would not mean the end of a series.

Stratemeyer offered Mildred the job of ghostwriting a new series about a girl named Nancy Drew. She accepted. She wanted to give readers a girl heroine who was different from any other at that time. Nancy would love to explore and find adventures in her everyday life. She would be intelligent and have a new kind of freedom about her. Mildred wanted readers to feel as if they were sharing Nancy's adventures and to dream about adventures of their own.

At first, Stratemeyer was disappointed with Mildred's Nancy. He thought she was too nervy. But the books were a huge hit. As Carolyn Keene, Mildred wrote 23 of the first  30 Nancy Drew mysteries. After she left the company, other authors (including Stratemeyer's daughter, Harriet Adams) took over the series. Mildred was sworn to secrecy.

For most of her life, Mildred kept the secret of her role in writing the Nancy Drew books. Even when her daughter came home from school, upset because no one believed her mom had written the books, Mildred kept silent.

Then in 1980, Geoffrey Lapin heard about a court case involving the publishers of the Nancy Drew mysteries. Harriet Adams was claiming to be the one and only Carolyn Keene. Geoffrey told Mildred and she appeared in court to identify the work releases that proved her authorship. The 'ghost' of Nancy Drew was uncovered.

Mildred Writ Benson lived to 96. She wrote many other children's books during her lifetime, as well as her own newspaper column. To many Nancy Drew fans, she will always be remembered as the 'real' Carolyn Keene.

(Note: The American spellings and usage in the passage have been retained.)

chum : a close friend

combing : searching through something carefully

antique stores : stores selling rare, old and (often) valuable objects

musty : smelling old and damp

roadsters : cars with no roof and only two seats

broke molds : did (something) differently from the way they had from the way they had been done for a long time

syndicate : organisation

quit : leave

nervy : (here) bold or daring 

secrecy : the state of keeping something secret