This video shows how to neutralize the lord regent at the dunwall tower in the return to the tower mission nonlethal and undetected. It also shows how to get to and talk to the propaganda officer and how go get to and open the lord regent's safe. Note that I am doing this on the hardest difficulty without any upgrades, except blink which you are given. That is why I am not picking up any Bone Charms or Runes or any other loot since it is unnecessary.