In "The Showstopper" mission, start out at the main entrance with your normal suit (do not put on a disguise). Go to the back of the palace where the helicopter is located. There is a pipe on the wall that you can climb to the upper floor where the secret auction takes place. Enter the auction room and sit down in the chair. Then, just stay there until Dalia talks to you to get the "Meeting The Reaper" achievement.