Enter the door on the left side of the hallway after.
The wall at (B) will open, revealing two medikits and a demon on higher skill levels. Head down the hallway killing them, but be wary as you reach the halfway point. In the hallway, you'll encounter Shotgun Guys. Afterwards, you can turn around and open the wall (A) to open a larger area with a berserk. When you begin the level, you may have to deal with troopers in the cages to the left and right if you're playing on I own Doom! or Watch me die!.
