Don Corleone has blackmail evidence on a number of judges, which he keeps in the vault of Manhattan Trust. The Cuneos are planning to heist the bank; if they steal or destroy the evidence, the Corleones will lose their leverage with the law.
Reward: +7,500 Respect
When you get to Manhattan Trust, you will find the Cuneos are already there heisting the place. Try not to shoot any cops at this point. They won't attack you until you get to the vault room. Go around to the side entrance (on the north side) and go inside. For future reference, the room on the right contains a health bottle if you need one at any point (and a Cuneo so be careful). For now though, go straight ahead into the lobby of the bank, and sraight ahead again into that doorway. Watch out for Cuneos in the doorway and in the room beyond it.
When you go into the room, watch out for a Cuneo hiding behind a desk on the right. After you kill him, turn around and go through the next doorway which takes you behind the bank's counters. Be careful at the next left as there will be a Cuneo there. Kill him, then go through the next doorway, turn left, and then right to find the stairs leading down to the basement. Go down the stairs, then straight into the room ahead and kill the Cuneo hiding behind the wooden crate. Then turn around, go out of the room and turn left. Go down the hall and when you get to the doorway, shoot the Cuneo hiding behind the desk in the next room. Go into the room, but turn around immediately to see if there are any cops behind you. The reason is that this is the room with the vault, so any cops around will start shooting you now.
Next, turn left and go through the steel door with the bars around it. Take cover on the wall to the left and kill all the Cuneos you can from there. Then go into the vault, kill the Cuneo in there, and collect all the money. Then exit the vault and go into the room on the left, killing any Cuneos remaining in there. Walk over to the blue marker to collect the evidence.