[8.4.]. Mission 4 - Area 51: Rescue

Obtain and use lab technician disguise: Head forward, turn right around the corner, and go up the ramp, eliminating any patrolling guards. Exit the ramp area, turn right, and go through the opening in the crates. Continue to the end, turn right, kill the guard, and then turn to face the explosive barrel under the crates on your left. Crouch and grab the Double Falcon 2 where the barrel was. Return to the ramp, use the elevator to go to the next floor, and eliminate any guards waiting at the top. Exit the elevator and head right. Eliminate the distant guard, then return past the elevator and follow the catwalk to the right until you reach a large steel door. Go through it and kill any guards on the catwalk above, being wary of those using the elevator. After clearing all guards, return to the starting area with the crates. Use the Action button to push the crate back up the elevators to the top of the catwalk. Follow the black catwalk until you see a small X carved into the steel wall on your right. Position the crate in front of this wall and shoot it to create an opening. Enter the hole and proceed through the tunnels. On the other side, kill the scientist, take his Lab Clothes, and equip them to complete the first objective. Put away your weapons.

Gain access to autopsy lab: Go left, through the first door, and kill the guard. Take his Super-Dragon. Go through the door to the right of where the guard was, run past the next guard, and go through the subsequent door. A guard will allow you through. Run to the scientist in the rear right of the room, becoming uncovered. Kill any guards and scientists present, then go through the next door to complete the second objective.

Rescue the crash survivor: Exit the room, go right, and enter the door a few feet away on your right. Eliminate any guards, take the key card, and proceed through the next door. In this room, kill the guards and take the key card dropped by one of them. Go through the next door near the glass, turn the corner, and go through the next door to complete the third and final objective.