1. Compare staff/casualty lists: medium 
2. Recover CCTV tape: easy, medium 
3. Disable all security cameras: medium 
4. Escape with Natalya: easy, medium 

Addendum 
Silenced PP7s: There is a way to get two Silenced PP7's in this. There is a safe that can be opened in this level that will recover your PP7 and your dossier. If you go to the room that has six mainframes and one camera and one soldier, you will find a safe key that will open the safe near the prison from which you extricated yourself. This safe is the closest one to the jail cells. These guns are only available in the Agent and Secret Agent levels. 

This level is hard, but it's one of the best designed levels in the game. 

You're stuck in a cell and next to you is Natalya, who you meet for the first time. (Approach her cell and you'll initiate a conversation, but you don't have to talk with her if you don't want to). Check your gadgets. Switch to the magnet watch attract. Approach the side of the cell with the door on it. Across from you is a key, so press Z and the key will fly to you. Wait until the guard is really close to you and press B to unlock the jail cell door. The guard will bend down on one knee to shoot at you, when he stands up give him three judo chops (judo chop!). Take his KF7 Soviet. Switch to the watch attract magnet again, walk to the circular caged platform at the end of the hallway, press Z, and you'll pick up a set of throwing knives. 

You can let Natalya out by pressing B at the cell door, but don't. Go to the double door, look through the windows. Use you site and in the next minute you should see as many as three soldiers walk by. Knock each off with a blow to the head. Try to use only one bullet per soldier, otherwise you make a racket and the whole building will know you're there. If you're not that good yet, try to control your fire to a single shot, pause, and then another single shot, etc. Open the door, peak around the left corner, it should be clear, but don't go down the long hallway on your left yet. Go to the double doors ahead (which you'll need a security key for) and turn left. Another set of doors (which you can get through). Peak through the window. Three guards. Aim for one, peg him in the head, and stand back. The two others should come out. Try to be quiet while you end their boring lives. 

The basic aim here in this first part is to avoid the many annoying security cameras (which are everywhere) and find security keys. Go back to the long hallway and stop at the end. Soldiers will pass by. Wait until there's just one and then peg him quietly (one shot). At least three others will follow. Kill them as quietly as you can, too. Go up the short flight of stairs head straight. You're now entering an automatic gun area that wasn't in the easy level. At your first turn look up and ahead, the back of a big gun. Blast it. Run through the maze until you see a red light. It'll come after the blue light. Stop when you see it and the big automatic gun. Blast it. Walk ahead into that slightly open area and stop. To your right is another big automatic gun. Blast it. Stray soldiers will come from behind you every so often, so keep an eye out for them. 

There's a split in the hallways. Turn right and kill two gunmen and hide in the corner while you reload. Lean out and kill the guy on the other end of the hallway. At least a half dozen more soldiers in little batches will arrive from both ends of the little maze you're in, but if you're somewhat subtle, their march will end. Kill them all off and then peak out into the long hallway, but don't step out. There's a guard at the end of it. Pick him off with slow single shots. The coast should be clear. Run down the hallway and take your first right. Peep through the window, kill off one guy. The door will open, kill the next guy. You should pick up Keycard A also the Severnaya staff list. Cool. 

Step out of the room, take a left, go down the flight of stairs (you should recognize the area you're now in), go down the hallway, and take a left. The keycard will now open those double doors. If no guards are around then run like the dickens to the next set of doors. If you stop and look down the hallway, you're sunk. There are two guards there, plus a security camera. That's why you run. Turn around and wait for the dumb guards. Kill them. Now enter the double doors. Then look through the window, kill one guy through the window, and the door will open, followed by at least three guys. Kill them quickly and hide in the storage slot on your left. If no one comes, then one by one kill each single or set of guys who hide in those storage slots. If all goes well, then the room will be empty. Look around. There are two important items here. One is a red clipboard, and the other is a body vest. The clipboard will allow you to meet objective A. Grab them both and head toward the opposite door. 

Look through the next double doors. Knock out the camera. Go through the hallway, and instead of ascending the stairs on your right, pass them. There's another camera waiting for you there, so don't do it. Instead, circle all the way around to where you picked up the keycard A and the staff list, pass that room, and enter the long hallway. Walk down the hallway. You have several choices. First take out the most obvious camera in that hallway. Take one slow shot at a time. We've actually knocked one of these cameras out in one shot, but it usually takes three. Back up a few steps now. Take the first door on your left. Peak through the second set of doorways, and look left. Blow out the camera on your left, and then wait for the guard inside to move on you. Kill him and take his keycard B. More guards will arrive from outside. Keep their deaths somewhat quiet, and stay away from the mainframes so stray bullets don't blow them up. 

Leave the room, take a right, and don't move. Inside that room is a camera. Open the door and strafe right out of its site. Time your approach so that when you strafe back in its site, you blast it right off. If you blow this chance, you're history. Lots of guards will kill you. OK, once that's done, enter the room. Head toward the other door and look straight up. The nastiest camera in the game is way up on the wall. Blast it. Only two left. Enter that room and grab the CCTV tape. Yes! Now back out, and head toward the main control room. 

You're almost done, and there's only one camera left (thank God!). Peak around the corner. Two guards hover inside the glass encased room across the way. Two more guard the exit. Start picking them off one by one, but still remaining in hiding. After killing them off, get to the stairway closest to you, and switch to your Klobb (actually you should have double Klobbs by now). Kill off as many as two to four guys in that room. Descend the stairs. Head toward glass room across the main room. Make sure to stay against the wall. There's a camera up on the wall in there. Use your site and blast it. Almost done. 

Go get Natalya from out of her cell. She will follow you back to the main room, although slowly and sometimes awkwardly. Nonetheless, she will follow you. She'll check a computer, set off a timer, and then both of your should run the heck out of there. Use the glass door exit, run up the stairs, and depart. You're done.