This is the first part of the Fight Night Mission in Hitman: Absolution which is called the Patriot’s Hangar. In it you sneak past some guards, retrieve a key card to the backstage entrance and then make your way to the exit to get to Sanchez. This guide explains how to complete this mission on the hardest, purist, difficulty. It does not explain how to complete the different challenges in this area.
At the end of this guide is a YouTube video with a visual version of this guide.
Get to Sanchez
At the start go forward and around a corner to the right. Take cover on the pallet leaning against the stacked crates and wait for the guards to have gone away and one guard to have come close and turned his back on you:
Then go around the corner and behind the truck. Go towards the back of the truck and, once you are past the truck, make your way behind the crates:
Follow that area behind the crates all the way to the other end, and take cover on the left crate next to the last gap to the left:
Wait for the guard to have entered the space between the stacked up crates (you can just make his head out in the image above). As soon as the guard goes out of sight in that gap get out of cover and crouch walk into that gap too. On the left wall of the gap a little way into it is a key card. Pick it up and make you way back to the other side of the area behind the crates. Take cover in one of the last crates and wait for the guard you waited for at the start to have turned around and walked off to the right:
Then go behind the truck again and back into the starting area. Ahead is a door with a key card checker. Open that door with the key card and go into the room. Drop down into the elevator shaft and go into the air ventilation shaft. Make your way all the way to the other end of it and drop down into the next room. Go up to the door. Once you have picked the lock of that door and gone through it it is the end of this part of the mission.