This strip was originally interactive. Clicking on the piece of paper sticking out of the book produced the letter, and then clicking on the seal opened it. This is an animated GIF version of it. The letter is a cryptogram, which when solved, reads:
If you are reading this letter, then it is likely that I am dead, no doubt killed by one of my many enemies. I bequeath the magickal items in this safe to you. Please keep them safe, and tell no one of them!
Do not underestimate the power of these artefacts, and do not use them frivolously, for their magick carries with it a great cost. The book is particularly powerful, and there are those who would seek to gain possession of it. You must not allow this to pass, or there will be dire consequences!
I have done questionable things. I do not know what death has in store for me, but I sense that we shall meet again someday.