“LIBRARIAN – HAPPY EASTER X”, just  three words and a signature X was all it took to once again open one of Britain’s most intriguing literary mysteries of the 21st century. In November 2000, a pair of notebooks belonging to Charles Darwin, went missing during a “routine request” and photo shoot at Cambridge University Library’s Special Collections Strong Rooms.

Leather-bound and marked “B” and “C,” one of the notebooks contains a sketch by Darwin of his ‘Tree of Life’ theory. According to the BBC report on the story, “The notepads date from the late 1830s after Darwin had returned from the Galapagos Islands. On one page, he drew a spindly sketch of a tree, which helped inspire his theory of evolution and more than 20 years later would become a central theory in his groundbreaking work On the Origin of Species.”

The notebooks were discovered to be missing during a routine check, prompting an extensive search of the library’s shelves and archives in case of a misshelving. After over a decade of detailed combing, and with no clues as to their whereabouts, they were eventually declared missing, presumed stolen.

A BBC article in 2020 highlighted the books’ disappearance, prompting an international campaign by the library requesting assistance in their return. “This is the time to just safely, even anonymously, get in touch,” said librarian Dr Jessica Gardner. “It’s those new leads we’re looking for, with the help of the police, in order to help recover these for the nation.”

This month, more than over twenty years after initially going missing, the notebooks were returned in baffling fashion: packed plastic wrap and a pink gift bag, with a cryptic note printed on brown paper. The mystery remains: who took the notebooks and who returned them.