Speak with Sam when you're ready to head out to Lady Boyle's party. Just like with the rest of the objectives, you'll have to find a way to infiltrate the building in question, which involves sneaking past a new enemy type. The tallboy is a massive enemy, a mechanized guardsman of sorts that is operated by a member of the City Guard. Their massive stance makes them annoyingly good at spotting you as you slink about the environment. These big guys also pack rockets, which can take your health down fast.

Killing a tallboy is best accomplished with a drop assassination from a high point. You can also kill them using a Wind Blast move that's been upgraded after they fire a rocket at you; send the projectile flying right back at them. If you're going for the Clean Hands run, simply avoid them and make heavy use of Blink and time manipulation. If, on the other hand, you are game for killing some tallboys, and you can't get up high and you don't have the Wind Blast skill, just try aiming for the whale oil tanks on their backs.

Sneak through the opening area as best as you can. There's a Bone Charm, Rune and Outsider Shrine ahead that you should hit up before leaving the area. The large walkway ahead will take you into a weeper filled apartment. Head in there and use a sleep dart or Blink to get down the path unscathed. The red apartment at the bridgehead holds the Bone Charm. Blink through the top floor balcony and you'll end up right next to both the Charm and the Rune. The Outsider Shrine will be right there with it.

After you get the Bone Charm and the Rune, it will come time to sneak into the party. There are multiple ways of doing this, so check in with the next guide to be sure you're keeping in line with your playstyle.