Secret Diary is a rare crafting ingredient that was added in the June 19, 2012 Patch. It appears as a diary with a lock. One of the corners of the book is burned.
Unlike some other items, this item is considered extremely rare!
Equipping the Eliminating The Impossible set will change the Secret Diary description to "the deeds of hellish cruelty and none the wiser", with random characters removed, which is a part of a quote from the "The Adventure of the Copper Beeches" short story, part of The Adventures of Sherlock Holmes collection. When combined with the other items added in the June 19, 2012 Patch, the full quote reads "Think of the deeds of hellish cruelty, the hidden wickedness which may go on, year in, year out, in such places, and none the wiser."
This currently has no use in the TFHunt solving.
June 19, 2012 Patch
- [Undocumented] The Secret Diary was added to the game.
June 20, 2012 Patch