Investigate the steel mill - exploring the mill | Main storyline Batman: AO Guide

Using the grapple is a good idea to start the fights

Carefully, approach the new enemy group and try attacking the bandits by surprise, for example by knocking them down from the venting shaft below, or by throwing a propane tank towards them, using the grapple. Right after the fights start, start by targeting the enemy with the gun and do not allow the rest to gain access to weapons.

You need to rip the venting shaft grate off

After you are done with them, walk towards the door located in the North-Western part of the loading bay. Climb up the stairs and use the claw to gain access to the venting shaft above. Jump into the shaft and reach the Sionis' Office. I recommend that you start the fight here by throwing the concussion detonator towards the enemies around the automatic gun aimed at he office entrance.

Sionis's computer

Jump down and attack quickly the stunned enemies and focus mainly on the armed enemies. Later into the fight, do not forget about stunning the armored enemy with your cape. After the fights finish, approach Black Mask's computer to analyze it and acquire the Janus security code.

You now need to return to the lower area of the loading bay, where you need to remember to stay out of the range of the automatic gun in the corner so, you need to walk through the venting shaft again. This time, go to the door located in the North-Eastern corner of the loading bay. Select the Cryptographic Sequencer from the inventory and start the hacking mini-game that consists in determining the correct password (the screenshot). You can now open the door to the Loading Bay Depot [Warehouse].

If you want to, you can blind the enemies with the fire extinguisher

After you watch a short cutscene, attack the enemies gathered in the warehouse. Just like in the case of the other fights, it is worthwhile to take the enemies by surprise by, e.g. pulling the fire extinguisher towards the bandits, in order to blind them temporarily. Defeating the first enemy group should not be too demanding for you, although it is worthwhile to make sure that you dodge the elements thrown at you, to prevent losing healthpoints. Problems will arise with the arrival of reinforcements, because there will appear an enforcer, among others, who is heavily armored.

To stun the heavily armored enforcer, you need to use the cape stun attack three times

Focus on the abovementioned enforcer, while remembering to avoid his charges and avoid being grabbed. When it comes to the strategy of weakening this one, you need to use the ultra stun attack so, you need to triple-tap the cape stun key/button. Only then launch a combo of very fast blows. In the meantime, you should watch out for the standard enemies, although they are not too much of a challenge, even as a group. Keep fighting until you have eliminated all of them in the warehouse.

[New Character Trophy: Black Mask's Armored Enforcer]

[New Challenge: Combat Training (Combat Training)]

Use the claw on the suspended cargo

You now need to solve a relatively simple puzzle. Start by pressing the big red button, which will set the crane in motion. After you watch the cutscene, stop near the cargo suspended from the crane, which has already damage the upper wall a bit. Use the claw on the cargo and slam it against the wall, thanks to which you will open passage, into the next location, for yourself. You can now use the hook and reach the Concealed Room. Walk into the elevator [Elevator Access] and activate the evidence scanner after you have listened to the monologue. You need to scan the corpse, which you have found in the elevator, to learn that the person has been poisoned.

After the elevator reaches the next floor, walk into the neighboring corridor [Hidden Facility Maintenance] and surprise the bandits there with an attack. While fighting, watch out for the armored enemy and prevent the enemies from collecting weapons from crates. After you win the fights, approach the locked door, select the Cryptographic Sequencer from the inventory and begin the hacking mini-game. Since you are dealing with a third-level security system, you need to select the correct password from a dozen, or so, of the available ones (the screenshot). You may now enter the Drug Lab.