White Knight Spy

Starting
To start, go to Falador Park and speak to Sir Tiffy Cashien.
 * Tiffy: Ah, hello there player.
 * Player: Is there any way I could help the White Knights?
 * Tiffy: In fact, there is. Our spies have noticed there has been increasing activity involving the Black Knights. We fear they may have a new plot. I need you to spy on them.
 * Player: Sure, where do I start.?
 * Tiffy: One of our Knights has noticed that a Black Knight patrol near Port Sarim. Take them out and then pick up their armor.
 * Player: Will do.

The Patrol
Go to Port Sarim and travel to the altar there. Close by there will be four Black Knights, all level 33. While this may be an easy fight it is a multicombat area so they all will attack you. Using a Dwarf Multicannon should make this fight easy. Once done, pick up their army. You should now have a Broken Black Platebody, a Broken Black Platelegs, and a Broken Black Full Helm. With these in your inventory go back to Falador and speak to Sir Tiffy.
 * Tiffy: Is the deed done?
 * Player: Yes, here it is.
 * Tiffy: Oh dear, its broken. This will not work.
 * Player: What should I do now?
 * Tiffy: The Black Knights Blacksmith is currently in the Laughing Miner Pub in Keldagrim. See if you can get information out of him.

The Blacksmith
Go to Keldagrim and head toward the Laughing Miner Pub, the place where you found Commander Veldaban in Forgiveness of a Chaos Dwarf. Equip a bronze helm and iron chainbody and go inside. You will see the smith talking to two dwarves. Walk over and ask him to make some armor for you. He will ask you for the password, and you will get it wrong no matter what option you choose. This will cause him to refuse. Now go get him two Dwarven Stouts, the closest one being the King's Axe Inn which is in the city. Use the two on him along with 500 coins. He will then tell you to make it you must smelt iron ore, two coal bars, and one batch of coal dust. You thank him, and attempt to leave, but one of the Dwarves will attack you.

He is only a Level 55 and should be an easy fight. After the fight two Red Axe Hand Cannoneers will be appear outside the window and start shooting. Hide behind a knocked over table to avoid damage. Use Magic or Range on them to kill them. If you don't have any weapons with you a Steel Crossbow will be available along with some bolts. Once you kill them, more Chaos Dwarves will flood the inn, so either teleport out of there or outrun them. Now head back to Falador.

Making the Armour
To make the three pieces of armor you need level 48 Smithing, along with 10 iron ore and 20 coal ore. To make coal dust, use a hammer on one piece of coal. Once this is done go to a furnace and make a black bar. You need 10 Black bars. After this, go to an anvil, the closest one being in Doric's house. Once there, making the three pieces of armour. Now return to Sir Tiffy.
 * Tiffy: Do you know how to make the armour?
 * Player: Yes, the Smith told me how to. Also, it appeared that he was talking to members of the Red Axe.
 * Tiffy: Hmm, very interesting. We will have to talk about that later. Anyway, go out and make a platebody, platelegs, and full helm.
 * Player: Sure.
 * Tiffy: Finished?
 * Player: Yes.
 * Tiffy: Very good. Now go to Falador's Lodestone and a knight by the name of Sir Fer will be there. Talk to him to continue the mission.

Infiltration
Head to Falador's lodestone and speak to Sir Fer there. Go the Black Knights' Fortress and find Sir Fer. He will now follow you, like a familiar. Go the main entrance door, which is protected by a guard. Talk to guard to continue. Bring Sir Fer to the cell room and put him in the cell. All of a sudden, a trumpet blares and a guard tells you to go the front of the Fortress. Arrive there within 15 seconds or else your cover will be blown and you will lose your armour and be kicked out. A Black Knight tells you a possible White Knight has been spotted in Draynor Village and he wants you along with two other knights to go. Arrive there using any method and talk to the Black Knights who are in the marketplace. Places around Draynor will now be marked with an "Investigate" option. Investigate all possible locations and then report back to the Black Knights. Go back to the Black Knights Fortress and talk to Sir Fer. You will tell him about the machine, and he will tell you to learn where it is and disable it.
 * Player: Sir Fer! Sir Tiffy Cashien sent me.
 * Fer: So you must be the adventurer. Do you know the plan?
 * Player: No.
 * Fer: Oh, so let me tell you. You will equip the armour you made and pretend to be a Black Knight. Once you've done this, head to the Black Knights' Fortress and you will see me hiding behind a clump of trees. You will bring inside the fortress, with me pretending to be your prisoner. Once inside I will tell you the rest of the plan.
 * Player: I will meet you there.
 * Player: I have taken a White Knight as prisoner.
 * Guard: I can't let you in without the password.
 * Player: Uhhhh... Kinshra?
 * Guard: Correct. Take him to the cells in the eastern side of the fortress.
 * Knight 1: Did you hear about our new plan to defeat the White Knights?
 * Player: No, but please tell me.
 * Knight 1: Well, they are using some Dwarven machine to-
 * Knight 2: That's enough. Let's continue with the mission.
 * Knight 2: Did you guys find anything?
 * Player: Nope.
 * Knight 2: Hmm, maybe it was a false alarm. Let's return back to the base.

The Machine
To learn where the machine is, talk to Black Knights around the base. An "Inconspicuous" option and "Bully" option will appear, and use Inconspicuous near the Fortress and Bully on the Knights who are scattered across Ice Mountain. Once you have talked to enough Black Knights, you will discover that the machine is located in the catacombs below the fortress.

Go back inside and open the trapdoor. You will be in a large maze. Wander around the maze until you find a ladder that leads down, similar to the Chaos Altar. Once you arrive in the bottom, you will see the machine. Right-click it and select "Disable". To disable it you need a tinderbox and a hammer. After you've done this, a cutscene will play showing Captain Peter will arrive and see you have disabled the machine. He will then attack you. He is Level 100, so lower levels should bring food and good armour. Once you have killed him, go back to Falador to claim your reward.

Congratulations, quest complete!