Your objective now is to track down the source of the radio signal to locate Joker. Observe the meter on the right, it tells you the Joker Radio Signal Strength. As you move, if the signal gets stronger (toward MAX) then you are getting closer to joker. If it gets weaker (Towards MIN) it means you are getting further away. Use this information to locate the source of the signal. Start heading towards the source.

Around this point you should be getting a message from your batcomputer that Augmented Reality Training is available. AR Training is a side mission, you don't have to do it now (you dont have to do it at all) so you can choose to go do them later. However, we recommend you do it now:
  • The Augmented Reality Challenges are a fun way to improve your gliding and diving skills.
  • You get a cool Sharpnel Boost Upgrade allowing you movement across the entire city without touching the ground.
  • It is easy to complete if you just follow our Augmented Reality Guide
As you approach the Steel Mill you will hear Harley Quinn:
"As you know, Mr J is... he's...he's not himself, and the last thing he needs is any so-called superhero coming in here and stopping his recuperation.
That's where you come in, morons. You need to protect the Steel Mill, protect it with your life, because if you fail, I'll make sure your miserable lives don't mean zip."

When you reach the Steel Mill area, locate the radio tower (High structure) and head over to the top of it. You will then call Alfred telling him you need to find a route into the Sionis Steel Mill. Alfred will tell you that you can use the main chimey to get in. Your objective now is to access the Sionis Steel Mill through the main chimney. Jump to the chimney near the radio tower and fly down. You will end your fall on a wire, jump into a nearby tunnel. The steam from the furnace can boil you alive, you need to cool down the coals somehow.

Switch to detective mode, then select the batclaw. Aim Batclaw and fire it at the hatch. Pull down to open the hatch and release cooling water onto the coals. Then drop down.Hang from the edge to avoid the debris. Walk on the railing. Jump to other railing and go through door. Switch to detective mode and select explosive gel. Prepare explosive gel and spray it on the floor, then detonate it. Jump down through the hole you just created.  crouch through the low tunnel. Follow the pipes to locate the source of the steam. Shoot Batarang at control mechanisms to stop the steam. Keep navigating through the tunnel until you reach the big room with the henchmen. There will be lots of them, so the fight will be quite intense.

You will now contact Alfred and tell him that the Joke's holed up in the manager's office in the Steel Mill and that some of his goons dragged a doctor away. Find the doctor first, then deal with Joker.

Your goal now will be to save the doctor from Joker's thugs. Head through the door marked "Death Ride" and then keep going along the corridors. The Joker's men will be waiting for you behind another door, you should scope out the room to pinpoint their location. Use detective mode to identify potential threats. Take advantage of vantage point, a convert position from which to survey a location. Thugs carrying firearms will be displayed in orange. You will learn that they've got that doorway covered and that you need to find a different way to get past Joker's men. Note the Fire Extinguisher. It contains pressurized gas used to extinguish fire. There is also the Security Gate Override that opens associated security gates. Throw your batarang at the security override system. Walk on the Conveyor Belt. Jump up, the climb down and grapple to vantage point. Use vantage points to get behind enemies without being detected. Swing between the vantage points. Head to the platform above the goons carrying the firearms. Drop down behind the armed enemies to take them down silently. Use the silent takedown when directly behind the target. Take care of the other two thugs with a double takedown. Then dive through window. Use grapple to head to top of room and blow up obstacle there. Notice the Service hatch, a metallic hatch that allows access to maintenance locations. Scan for Structural weaknesses - Structurally weak walls and floors will collapse with a controlled explosion.

Locate the door to the Smelting Chamber and go inside. Use crouch to move silently and quickly. Use corner cover and wait until the two thugs are close together, then use the double takedown to take care of those two thugs near the entrance to smelting chamber.

Defeat the rest of the enemies in the smelting chamber. Floored enemies can be finished off with a Ground Takedown.

Pry open the vent hatch and go through conveyor belt to nearby room. Youll have to kill the thugs before rescuing Stacy Baker. Note that using the knockout smash instant finishing move will alert nearby enemies. Free Dr Stacy Baker once you have dealt with all the enemies in the area.

She will tell you that the Joker has some sort of Toxin in his blood and that its killing him. He blames something called Titan. Suddenly Harley Quinn will say she is sealing you in and the door will become sealed. batman grabs the remote electrical charge (REC) gun. This electronic gun can be used to open electronically controlled doors and activate electric machinery. It deploys a high current charge to power generators and electromagnets. Can be fired at enemies to administer a localized non lethal electronic shock.

Your objective now is to break into the Joker's office in the Loading Bay. Switch to detective mode. Use the remote electrical charge to proveide power to motorized devices in the environment. Go through Cooling tunnel D. Locate the industrial electromagnet, an AC motor surrounded by electromagnetic field. This can be powered using the electric gun. Use that to pull the minecart and get the Riddler trophy.

The door out of the Smelting chamber will be welded shut. Switch to detective mode. See the Exit electric sign on the door nearby. There is a motor under it. As you aim the electric gun at that motor, two arrows will appear. Use the buttons that make it go up and down (RB and RT on xbox or R1 and R2 on Ps3). Fire at the door and use the RB button to open it.

Go through the door and head back to the loading bay, its the only route to Joker. keep using the electric gun to open closed doors on the way.

Defeat the thug at the other side of the welded door. In the Loading Bay, use the electronic gun on the machine in the south of the room. This will mobe the big metal hook. keep doing so and the hook will swing and smash the wall through which Harley Quinn retreated.

There will be a boss fight now, Mister Hammer. Quickfire the electrical charge. Try to get rid of the thugs first before focusing on Mister Hammer. Watch out for his hammer swings, as you take a lot of damage from his heavy hammer. After you take out his minions, a good strategy is to run in, do your thing, then run out before he swings his hammer at you.

Harley Quinn will cry. Hop onto the top door. You will enter the room with Harley and Joker, who is on a wheelchair. Scan the Joker. Suddenly the real joker will surprise you from behind and gas you, turns out that the joker on the wheelchair was a fake. Batman will lose consciousness.