Interval 01 - Inception
Objective: Investigate Area for Signs of Paxton Fettel
This is going to be a fairly slow level for you. You'll get a few tutorial prompts here and there, which will let you know how to crouch underneath obstacles or interact with your environment. Although you have a pistol, you don't have any real need for it, as there aren't any enemies for you to interact with.
One thing to note here is the appearance of a Health Booster in one of the rooms near where Janikowski busts out a window to talk to you. Grab it for a permanent boost to your health total. Beyond that, there's not much to see here except for one very, very dead corpse, and a chance encounter with the Paxton Fettel that you're looking for, on the rooftop of the building. There's no way to avoid what happens here, so return to the corpse when you regain control of yourself to leave the area.