From the main menu simply navigate to the "Campaigns" section then go into the "Hitman 3" scroll across to "On top of the world" Select and play.
As soon as the mission starts run up the stairs in front of you and take a left. As soon as you turn left you will see a small crowd next to a bar head over to the bar and wait for the event staff member to come out inspect the food and return into the back room(For me he was already going into the back room).
Follow the event staff member into the room wait for the door to close behind you and subdue him, once he is subdued take his clothes. Run to the left and enter the double doors that lead into the kitchen run around the room and leave to kitchen. Turn right then make an immediate left you will find a set of stairs.
Go up the stairs there will be 3 flights in total once you have reached the top of the stairs run straight down the hall don't enter the penthouse reception go to the right and make your way down the hall through the double doors. One through the doors run down the hallway on the right. Follow the backstage round to the right and you will come across two automatic sliding doors go through them.
Now outside turn left and you will see a ladder go to the ladder and climb it. Once you have climbed it look to your right you will see two guards you need to wait till one of the guards starts walking away and subdue the other. Make sure you drag the body to a safe spot before the other guard returns, Now take his uniform climb onto the helipad and walk around the helicopter.
Continue walking on the left hand side go through the automatic door and run into the security room. on the far side of the office you will see a safe on the wall. Go to the safe and type the code 6927 and hit OK, the locker will open and inside is an evacuation keycard take the keycard and go back out the door you entered from.
when you leave the security room take a right and go up the stairs into the penthouse. Once you reach the penthouse run past the two guards talking next to the emergency card swipe and two parachutes. Run past them turning right, From here you can see the kitchen area go into it behind the counter and take the knife from the side.
Now you have your knife go back to where the two guards were stood. If the haven't already wait for them to leave. Now open the chutes and sabotage each one of them. Once sabotaged swipe the first card swipe location, turn left into the study and climb the staircase. When you get to the stop of the staircase you will see the second swipe location, Go ahead and swipe. if you have done this fast enough both targets will begin to evacuate.
Go back downstairs to the first swipe location. go through the doorway on the left and take a right. this will lead you outside the penthouse. You will see two tracks one going left the other going right with a tree in the middle, take the left trail and follow it. Eventually you will be lead outside to a small golf range wait behind the chairs for the targets to come.
After a while both targets will come and jump off the building to their deaths wait a moment and the game will lead you to the exit points. lucky for you one exit point is right in front of you walk up and exit this is start a parachuting animation in which 47 will escape via parachute.
Once they fall the achievement should unlock. if it doesn't not to worry simply wait a moment then escape off the side of the building the achievement will then pop.