This is located in the
Paris mission "
The Showstopper".
There are multiple steps necessary in order to trigger everything, but you should keep in mind that Viktor Novikov will only walk the stage if the fashion designer Sato cannot be found.
The easiest way to accomplish this task is to sneak to the left from the start of the mission, jump over the far gate, use the generator to lure a crew member, and take them out for their disguise. From there go to the fashion preparation room and run the diorama using a coin when Sato is standing nearby. This will stress him out, and he will go for a cigarette. At this point, follow him, take him out and hide his body. Now go to the second floor and you should find a waiter alone in a room. Take him out for his disguise and make sure you don't have a weapon on you. Go to the third floor now, and accept the frisk. At the top of the stairs, find the door to the attic. Follow the attic to find a crowbar in one of the windows, then climb out a window and get on top of the light rig. Wait for Novikov to show up and start walking down the runway at the end of the show. Use the crowbar on the winch to drop the rig and kill him, unlock this.