Judge, Jury, Executioner

First things first, when you start this mission, you'll have a chance to grab another Glyph. Head to the building where Uberto is located. You'll want to climb to the roof on the north side. Watch out for archers up there – be ready to use your Hidden Blade for some quick counters if they spot you. Once you've dealt with them, activate your Eagle Vision to find the Glyph.

After that, you'll get a database file for Uberto and a video to watch. Once that's done, the real mission begins. Your main objective here is to go completely unnoticed. Drop down from your current position and immediately find a group of people to blend in with. Let them escort you around the building. It's crucial to stay blended, not just because of the regular guards, but also because there are Brutes around – they're a real pain to fight. Remember, even though you have the Hidden Blade, getting spotted at any point means you'll have to restart the entire mission.

Keep moving around the building, staying hidden within the crowds. When you get the chance, ditch your current group and find some Courtesans. Hire them and walk alongside them. Some of them will split off to create distractions for the guards. With the remaining Courtesans, make your way to an opening on the left side of the building that will allow you to get inside. You'll probably lose the rest of the Courtesans at this point, but that's fine. Just blend in once you're inside.

Now, keep an eye out for the red marker on your minimap. This shows Uberto's location. Continue blending with different groups, moving closer and closer to him. Eventually, he'll spot you. Walk right up to him and take him down.

Once Uberto is dealt with, your final task is to return to Paola's location.