1. Rappel off of this ventilation stack.
2. Enter the building through this open window.
3. Beware the patrols. You'll also hear the familiar beeping of a surveillance camera, visible in the far-right corner.
4. Take out the guard, then take out the camera. Hide the body near the window. Use the computer and discover that thermal optics will allow you to see the laser grid.
5. Exit through the door under the camera then sneak through this door.
6. Ascend the stairs and take the med kit on the wall.
7. Position yourself on the makeshift ramp as shown above.
8. Wall jump to this beam.
9. Jump across to the beam ahead.
10. Jump up to the beam behind you, then hop across to the ledge with the med kit and disposable lock pick.
11. Jump back down the way you came. Note that this jump is best performed by running off the beam, with no jump at all.
12. Take out the two guards in the hall, then pass through the door visible in the background -- be careful, there's a camera above the door.
13. Shoot out the camera above the door.
14. Use this computer to read an email. Use the computer on the opposite desk to learn that the courtyard's laser grid sensors can be deactivated by using the computer in the South Wing Main Hall.
15. Pick the lock on this door.
16. Once on the balcony you learn that only Colonels can open retinal-scanner locked doors.
17. Backtrack to the stairs, this time descending. Shoot out the security cameras on your way down.
18. Exit through the bottom door and shoot out the security camera directly ahead.
19. Don't shoot this security camera, that would alert the guard. Sneak around it instead.
20. You'll find Grinko's driver to the left, taking a whiz. Interrogate him to complete the objective.
21. Backtrack up the stairs to this room, passing to the balcony again. This time you'll see a mini-cutscene.
22. Climb onto the railing then shimmy along this ledge.
23. Shimmy around the corner then drop into this window. This completes your objective to infiltrate the south wing.
24. Pick up one of these bottles, throw it into the freezer, then sneak out this door while the cooks are distracted.
25. Sneak past the guard through this door. Turn left.
26. Climb over the balcony. You can safely drop to the lower level without alerting the guards.
27. Repeat the procedure on the next balcony. This time be sure to crouch before you land or else the guards will hear you.
28. Grab this guard from behind and knock him out. Hide the body under the stairs then use the red computer (just visible here) to deactivate the laser grid.
29. Next up is this colonel who descends the staircase.
30. Take him to the retinal scanner then pass through the door.
31. Knock out the colonel on the other side of the door and take his satchel for a medical kit.
32. Knock out the security camera and pass through the door below. A mini cut scene follows.
33. Quickly select the Laser Mic from your inventory.
34. Press AND HOLD your "Use/Equip" key and aim the laser mic at the glass elevator.
35. The indicator turns red while the conversation is being recorded. Keep the site on the glass elevator all the way to the top. NOTE: If your game refuses to advance past this objective, make sure you have installed the latest patch.
36. A disposable pick will quickly get you past the indicated door. Inside you'll find a medical kit and a switch for the courtyard lights.
37. Climb this lattice to the open window. Mantle up to load the next level and a mini cut scene of an approaching elevator.
38. Hide in this spot before the elevator arrives. The guards split up, making it easier to take them out. Hide the bodies in the utility closet to the left of the elevator.
39. Take the elevator up. Upon exiting, beware the security camera to the right.
40. Shoot out the security camera behind this soda machine.
41. Approach this door and a guard appears. Take him out.
42. Pick the lock on the neighboring door and enter this office. Use the computer to read an email. Hide the guard's body in the dark corner.
43. Mantle into this duct above the desk. Turn around so you are facing the clock and continue through the duct.
44. Drop below and shoot out this security camera.
45. Through this door you'll find a medkit on the left wall, ammo on the right shelving and a ladder which will take you to the roof.
46. Rappel down the wall.
47. Jump on the window to break through the glass. Kill the guard inside then use the red computer to update your objectives.
48. More guards pour in. Defeat them while the upload continues.
49. Lambert needs more data. Go back to the computer and use it to fulfill the objective. Kill any guards that enter the office.
50. Use this computer to read an email. The guard pictured left has a satchel with a frag grenade. You can leave the bodies -- they know you're here.
51. Head right out of the office to this room around the corner. Use the computers to read a pair of emails.
52. Backtrack to this previously-jammed door.
53. Pick up the med kit and head through the door. Ready your weapon and back out along the rear gangway. Kill the guards as they approach.
54. Take a running leap into this elevator shaft.
55. You'll grab onto this central support. Slide all the way to the bottom, listening to a firefight as you descend.
56. You'll emerge in the parking garage. Talk to Jr. Wilkes to complete the mission.