Getting to the highest point in the area appears to start in the lowest point - the Sewers. Well go figure, as nothing else has made much sense in this adventure so far... I mean what motivates a guy like Crane to DO this sort of thing??
Follow the marker to the underground bathrooms and through the hall there into the Sewers - where you will find an instance zone door to use. Follow that and you will reach a point where you hear a kid crying - this thing is a Super Screamer - you need to back off and shoot it
After you take out the Super Screamer a Brute will break through the wall at which point you have to deal with it and a never-ending supply of runners and regular infected. Basically you want to make as short a work of it as you can as quickly as you can - and the best way seems to be with a sword that has the flame ability built into it. Just saying that was what we used and it went down pretty quick as a result.
Once the Bruiser is out of the way you head down that tunnel to the gate, open it, and go through the pipe to the next area. In here you will come to a large room where you drop down the ledge and take out all the Toads inside, then go back up and through an open door to the deck above, and work your way to the other side using the pipes
Jump to the deck on the side of the room then walk over the blue pipe to climb on to the center deck. Use the yellow pipe to cross the room and drop down on the far deck then make your way to the ladder and use the blue pipes above to move across - jump and grab the next blue pipes and make your way to the deck on the other side and drop down, then jump across and go through the door.
Here is the thing - you may not have noticed this but the clock has been locked onto midnight since you entered the Sewers - basically the game intends for you to exit in the middle of the night - it really does not matter WHEN you went in - that is just the way that this mission is meant to play out...
When you emerge from the Sewers however night officially ends - but as it is raining you cannot tell that very well. You need to tun and jump and dive into the water and then climb out at the foot of the dam.
You will talk to Savvi who will give you some bad news - and then you will go in search of the keycard!
The first area does not yield a keycard, When we reach second area there is a pair of Brutes and a bunch of infected here as well as a Toad. Basically you want to shoot the Toad as quick as you can to minimize the damage it can do to you with its ranged attack, then take out the Brutes with headshots and the other infected however you please.
Once you do that you can search the containers until you find the one with the keycard (and the runner's body) and voila! You are good to go!
Head for the marker and make your way up the mountain pass, then over the fence. There are Bombers inside and Toads on the area above so avoid the bombers till they blow and then kill the Toads fast.
After that you can either avoid the rest of the infected (including a Hammer Brute) or kill them. Either way make your way to the door to the power substation and open it with the keycard and then go in - Savvi will tell you what to do.
You reach the antennae and you use the power box to call the lift - and as you wait for the lift to arrive everything goes all pear-shaped as the cable snaps, the lift falls and runners and Virals attack! Really?!
Look if you die a few times here do not get upset - it appears that this blitz attack was designed to have just that happen. To cause you to die and maybe die again. If you did not, well good on ya but considering where we were standing when the lift fell, that is not all that likely.
Right so when you get to the gap in the stairs you probably will think you are supposed to jump across. Well you are not. What you are meant to do is to jump out onto the strut here and climb that then jump to the next deck level. Look for the looped rope to see where you are supposed to jump at.
Now here is where it gets tricky - once you get to the top as far as you can go, you are expected to jump out at the antennae mounts that are hanging on the side. This is tricky and do not be upset if you die - I know I did.
Use the antennae mounts and the yellow and black striped bars to climb to the top and then install the amplifier. That kicks in the CS in which you call off the bombs - then GRE contacts you and offers you a way out.
They want you to come out with the Doctor's research - and they will send a chopper for you.
After that you talk to Savvi again and then you get a call from a stranger who asks you to meet them at the Vehicle Manufacturing Facility.
Side-Quest: The Launch
After that you unlock the Achievement: Vertigo (25g) Activate the Amplifier.
Now it is time to slide down the zipline then enter the tunnel and if you are like us you pretty much ran past the heavies and into the smaller hallway. About midway through that you get attacked by a pair of Volatiles. Now chances are if you have been avoiding the night these will be the first ones you actually HAVE to kill!
Killing them unlocks the Achievement: Mouths Wide Open (25g) Kill a Volatile.
With them dead and hopefully not you - heal up then continue through the hall to the marker, making your way past all the infected, up and over the semi trick and through the door. Jump down into the Sewer and swim to the other entrance and then climb out.
From here you just need to exit through the door to Old Town.
That wraps up this mission.