The lost notebook of Alan Turing, the mathematician and computer scientist recently brought to life by Benedict Cumberbatch in the Oscar-nominated film The Imitation Game, will go up for auction at Bonhams on April 13 at the Fine Books and Manuscripts sale in New York. Filled with his work to crack the Nazis’ Enigma Code, the notebook is expected to fetch over $1 million.

The 1942 notebook, hand-written while Turing was working on the Enigma Code at Bletchley Park, is 56 pages long and is said to include computations that provide the foundations of computer science. The manuscript comes from the collection of Turing’s friend and fellow mathematician, Robin Gandy. He had kept the journal, rather than donating it to Kings College, Cambridge, along with most of the other Turing documents he had inherited, using it as a dream diary.

In a statement, Bonhams claims that the notebook is “almost certainly the only extensive autograph manuscript by Turing in existence, and has never been seen in public.” “Its mathematical content gives an extraordinary insight into the working mind of one of the greatest luminaries of the 20th century,” added Bonhams’ specialist Cassandra Hatton.

Turing had a tragic life story. A gay man who was convicted of gross indecency by the British government and forced to undergo chemical castration, Turing committed suicide at 41. The Imitation Game, the biopic of his life, has been nominated for eight Academy Awards, including Best Picture, Best Director, and Best Actor, for Cumberbatch’s portrayal of Turing.

Cumberbatch called Turing a war hero in a press release, adding that “his impact on our everyday lives is enormous, and the thought of being able to hold a manuscript that was written by him is thrilling.” The market for Turing related writings and memorabilia has seen a significant upswing thanks to the film (see Hollywood Collectors Snap Up Nazi Code-Breaker Alan Turing’s Papers).

“Turing was parsimonious with his words and everything from his pen has special value,” said Andrew Hodges, whose biography was the basis for the film, in a statement. “This notebook shines extra light on how, even when he was enmeshed in great world events, he remained committed to free-thinking work in pure mathematics.”

For more artnet News celebrity-penned manuscript coverage, see Bob Dylan’s “Like A Rolling Stone” Lyrics Bring $2 Million at Auction, Jane Austen’s Unfinished Manuscript Gets Museum Show, Beatles Sold! John Lennon Manuscripts Score $3 Million, and John Lennon Letter Praising Yoko Ono Fetches $28K.