Bloodstained Letter

 is a tome in Act III of Diablo III. It can be found in Keep Depths Level 1 (sometimes 2 or 3), obtained from a Dead Soldier. It is needed for the Primary Sources achievement.

It reads as follows:

''My dearest Jonathan, I hope this letter finds you well and that life at Bastion's Keep is not too difficult. Arthur is growing up to be just like his father. I'm happy to hear you'll be back in time for his birthday, and I'll be praying every night for your safe return. &mdash; Brielle''