Yesterday we learned that Harry Potter author J.K. Rowling secretly published a new book in April called The Cuckoo’s Calling under the pseudonym Robert Galbraith.

So how was the hidden book finally uncovered?

The New York Times spoke to the editor of the U.K.’s The Sunday Times who broke the story late Saturday evening.

As it turns out, one of The Sunday Times’ writers had read The Cuckoo’s Calling recently and tweeted her appreciation of the book. Shortly after, an anonymous person replied to her on Twitter and told her that J.K. Rowling was the real author.

When the editor replied to the Twitter user asking “How do you know for sure?” the user said “I just know,” and then proceeded to delete all of their tweets as well as the account.

From there, The Sunday Times decided to dig. They connected the dots between the publisher and editor of The Casual Vacancy and The Cuckoo’s Calling (they’re the same), and sent the two books plus Harry Potter and the Deathly Hallows to linguistic experts who found “significant similarities” between the three.

With so many connections, The Sunday Times e-mailed Rowling’s publicist on Friday night a simple question: “I believe that Robert Galbraith is in fact J. K. Rowling, and will you please come back with a straightforward answer?”

It was then that Rowling decided to come clean. She issued a statement about The Cuckoo’s Calling and told the world it was great to publish a book quietly.

The New York Times goes on to reveal that a second print run of The Cuckoo’s Calling is now underway, and “will carry a revised author biography, which reads ‘Robert Galbraith is a pseudonym for J. K. Rowling.’”

Since this revelation yesterday, the book has skyrocketed to the top of the Amazon U.S. and U.K. book sales charts.

The New York Times revealed that only 1,500 copies have been sold in the U.K. so far. The number of sales in the U.S. is not yet known, but we’ve heard from at least two Hypable readers that the book was featured in summer reading sections at their local stores because of positive reviews.