This is the level where you should be getting the achievement "Silent Victory". On this level, you will automatically be Taggert. Just run through the level and take cover when needed. Hide in some cells and with your knife, guard the door until you have full health again. When you do, run out of the cell and slash your way to your destination. Also, throw grenades and fire your machine gun. Save the man, and run out. Take your time and heal when needed. Your teamate will not die, so let him shoot some enemies down.