Run through the door and continue running forward. Open the vault door and run ahead. Use the zero-G jump to move out into open space. Run forward and along the path and aim forward to a vault-like opening to advance through. Keep moving ahead in a straight line. You'll come to a door. Turn around to the right and advance through the door to the right of the store. Run down the hallway and keep going until you hit your first left. Continue down the hallway riddled with dessicated corpses. Dispose of the Necromorphs here. Continue down the hallway and run through the door. Take the lift up and take out the Necromorph that pops out of the air vent. Turn around and advance across the bridge. Turn right and run forward, then turn right again and cross the next bridge. Turn to the left and follow the catwalk around to the lift here. You'll need to, of course, fight off a wealth of enemies here to advance. After riding the lift down, run to the left and head through the vault door. Run down this corridor, continuing straight. Open the next door and head through it. Turn to the right in here and slash at the power node. Then open the next door and curve around to the right. Once you've crossed the threshold, another lockdown ensues. Eliminate all threats and advance through the door across from the one you entered. Slash the power node here to the left and continue through the next door. Keep running straight through the next door and down the hall. Take a right an go through the next door. Slash the power node to the left here. Continue forward. Go straight. Head through the vault door. Ignore the path to the left and go through the next vault door as well. Run forward through the large expanse. A lockdown ensues. Eliminate all enemies. Once you've done so continue forward through the door. Run straight down the hall and curve around. Take the first door outlined in blue. Run across the bridge into the tram. Once aboard, you'll need to fight your way to the end of the chapter.