Crash the Bludhaven Police Department
As soon as Harley’s mission starts you’ll find yourself in the Bludhaven PD’s garage staring down 7 police officers. This will be your quick introduction to how Harley controls in a fight. She isn’t too different from Batman, with a Jack in the Box doubling as explosive gel, a snare attack to bind incoming attackers, and laughing gas that works like a smoke pellet. She has a baseball bat that’s used like Batman’s cape stun and is used in some pretty brutal take downs.
Familiarize yourself with the way Harley fights here, and take down all 7 cops. Once that’s done you’ll be prompted to head through the door and into the break room area.
Once inside the game will have you enter Psychosis Mode which functions like Batman’s Detective Vision. With it Harley can see through walls, as well as see crazy writing scrawled over every surface. She’s insane, what do you expect? Hell, if you stay Psychosis Mode for a while, Harley will even start to talk to herself!
In Psychosis Mode you’ll quickly see that there are three police officers around the corner in the break room. Place a Jack in the Box on the ground and then hide in the nearby grate. The officers will be alerted to the music from the box and come investigate. Once all three are near the box detonate it to take them all out instantly.
Pop out of the grate and you’ll notice a staircase leading to a doorway that’s currently barred shut. This is where you need to go. Getting there is pretty simple, just round the corner into the break room and you’ll notice a grate in the ceiling above. Use Harley’s acrobatics to climb up there, and head over to a wall that looks destructible (in Psychosis Mode a comic-book style BOOM will be overlaid on any destructible surface.)
Set up another Jack in the Box here and detonate it to watch the wall go boom. From here you can leap down into the stairway you saw when you came in. Access the door at the top here and head into the building’s control room.