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III. Rescue The Scientist

After the cutscene ends, walk around the wall with the “Rescue the Scientist” on it. Hit your goggles with Up on the directional pad to check out the enemies in the area. Make a quick right and move up behind the guard standing there with two other guards in front of him, but WAIT UNTIL THEY FINISH TALKING! After they finish talking, even though you don’t have Execute ready, mark the two guards with the Right Button anyway. Next, hit B to melee kill the guard standing in front of you. This will make your Execute ready to kill the remaining two guards, so hit Y immediately. After you Execute the guards, kill the human shield and move on.

Before you move on from this point, mark the two guards to the far left of you in the next room. After you’ve marked them, walk directly in front of you a few clicks towards the pipe along the wall. Hop on the pipe and climb all the way into the next room. You will be directly above a slit in the room where a guard is pacing. Perform a Death From Above with the Left Trigger on the guard and IMMEDIATELY perform execute on the guards. YOU WILL BE SEEN! It’s okay it is a part of the mission. A few more guards will run in so take them out. Shooting enemies in the head is the quickest way to kill them so aim high.

[EDIT] If you shoot the light out from under the two guards, they will be aware of your presence, but you can sneak around them when they come looking for you. After you shoot the light out, climb the pole and head across until you get to the next room. Fall down from the pipe and head through the door. You will have to use your sonar to see them since the room will be fairly dark.

After the wave of enemies are dead, walk through the entrance into the next area where you will see a flight of stairs on your left. After walking up the stairs you will see three enemies alert of your presence and are anticipating you. Walk to the rear of the room and hop down on the ledge. Mark the 2 guards on the other side of you then perform a Death From Above on the singled-out guard. After you kill him, Execute the 2 guards. Walk towards the mission arrow and you are all set!