If lost or destroyed, a new copy can be obtained by searching the wardrobe again or from the bookcase in your Player-Owned House made through Construction.
Below is the text you can read from within the book.
I have recommended you to Captain Dulcin, as we agreed.
He'll provide whatever supplies you deem necessary.
I have ensured that he will extend you every courtesy. He suspects nothing.
Strength through chaos, my witch,
Leader of the Black Knights