Now that the attack has been called off you called Dr. Camden and he is waiting for you to deliver Dr. Zere's research - so get to it!
The first step is to return to the original Tower. Head upstairs and talk to Selma who will thank you for saving her son - remember that? After you wrap up that conversation you remove the “!” so head back down the lift and Fast Travel back to Old Town.
Re-supply, see to your weapons, then head towards the marker on the map - when you reach the building use Firecrackers and Molotovs to clear away most of the infected from the entrance and then drop down and head in. There may be some infected inside but there will only be a few.
You then unlock the Achievement: Now You Can Come In (25g) Find Camden.
Follow his instructions with the lift and you zone into the Instance. Dr. Camden explains what you need to do - and while he is doing THAT he reveals a LOT of information. For example both he AND Dr. Zere were working for the GRE. That Rais was supposed to protect them, and if you keep listening you may be getting a bad feeling - I was.
In the woman’s locker room is the entrance to the duct that gets you into the Security Room. Grab the keycard there and open the door with the computer.
To get to the power room and turn the generators on you need to work your way through the ducts from the lab into the chemical storage rooms and use the forklifts to clear the path - the first you lower, the second you raise. Once that is done you start the two generators that still work and then head back to decontamination.
When you finally get to Dr. Camden he takes the samples and starts working on them. You learn that Amir was a GRE operative - strange. He warns you to be careful with the GRE - well it seems that he is not totally in their employ!
When you emerge it will be deep night - so carefully sneak your way to the Safe Zone at the University via the rooftops, then sleep till morning and then go out and contact the GRE.
You have a conversion with - Rais! Well that was a surprise.
This completes the mission.