Chapter: The Stratford Tower
Towards the end of the mission when you reunite with your team you will have some choices to make. Make sure you choose RUSE and knock both guards out (DO NOT ASSAULT). After both guards are incapacitated enter the room and not to long after a staff member will try to escape. Make sure you SHOOT, therefore he will be unable to raise the alarm. Proceed with the rest of the mission and jump off the roof.