Start by looking for Eluned at either one of the Roving Elf spots shown on the Map of Isafdar. You might want to wait at a spot or not. Talk with her, she says Arianwyn Requests a meeting with you in Lletya. She will take you there if you say yes.

Once you're there, you'll receive a Teleport Crystal with 4 uses. Use this to teleport to Lletya. You can recharge it for 750gp from Eluned, but you'll only get 3 Charges instead of 4.

 

The Mourner's Outfit

Arianwyn will inform you that the Mourners are in fact Elves, and that there has been many sightings in the mountain pass in Arandar. Head to the mountain pass and wait for a Mourner to come by. Attack him, and he will throw a vial that reduces your hits and other stats to 20, but that shouldn't be a problem if you brought food and potions.

Once he is dead, you will get a Letter and a full Mourner set, although 2 of the pieces are unusable.

Bring the Broken Trousers to Oronwen in Lletya with 2 Silks and 1 Fur. She says that these pants are made for Elves but are not made by Elves. She will fix them, and you will be able to wear them.

 

To clean the blood stain from the top, go to the lake south of Taverly, and ask Tegid about cleaning blood stains. Steal his Soap from the Laundry Basket and use it with the jacket while carrying a Bucket of Water.

 

Infiltrate the HQ

Now you are ready to infiltrate the Mourner's Headquarters. Make sure that you have feathers, soft leather, a magic log, 2 Toad Crunchies and your Letter.

 

If you remember where you have sabotaged the Mourner's soup in the Plague City Quest, this is the place to go. Check the Ardougne Location Map for the important places.To enter, you must only have your Mourner Set equipped. Go downstairs through the trapdoor. Talk to the real Head Mourner, and you will get some interesting info on what's going on. He will ask you for paperwork first, so hand him the Mourner's Letter.

 

After his story, he will need you to re-dye The farmer's sheep (from the Sheep Herder Quest), but, the device is broken. He will give you a key and a Broken Device, which the Gnome next door can fix.

 

You will need to use feathers on him twice, show him the crunchies after, and then he will tell you to bring the materials to fix it (a Magic Log and Soft Leather). Wait a bit and talk to him again to get your fixed Strange Device.

 

Now you will need to make some ammo. Remember those 4 Colored Sheep groups in the Sheep Herder Quest? Well, those are the ones that you must re-dye. You can get Dye From Lletya's Clothing Shop Or Aggie in Draynor However, to Re-Dye the Sheep, you will need to fire an ammo of some sort on them.

 

The ingredients for each dye are as follows:
Red - 3 sets of Red Berries & 5gp
Yellow - 2 Onions & 5gp
Blue - 2 Woad Leaves & 5gp
Green - Mix a Blue and a Yellow Dye together.

 

You need 1 dye per toad, and you need to hit the Sheep once with the corresponding color for them to be colored properly. Head over to the toads from the Big Chompy Bird Hunting Quest, make sure your bellows are empty, and use a dye on the bellows. Use the dyed bellows on a frog to get a frog of that color. If you need help finding the area, check out the Chompy Hunting Grounds Map.

 

Get 1 Frog of each color. If needed, you can take extra frogs if you think you may miss. To shoot, add 1 Frog to the Ammo Chamber of the Device, select the "choose attack style" option, and select aim and fire. In the top left corner you will see what ammo is currently being used. If you need help finding the sheep, check out the Sheep Location Map.

On the Bottom right, you'll see 4 Directional Arrows and a red button. Aim with the arrows and shoot with the red button. You only need to shoot one sheep of each group. They will be significantly more colored if shot correctly, and you won't have the option to Prod them anymore.

 

After you have dyed all 4 Sheep Groups, Report back to the head mourner. He wants to know:

1. Who made the poison.
2. What the poison was made from.
3. How the poison can be made.
4. Produce enough to poison a lot of people.
5. Contaminate the food store.

 

Apple Mush

First, Go to Elena 's House, which is located on the west side of the river from the Biohazard Quest. Talk to her, and after telling your story, she wants a sample of a Rotten Apple. Now, between the Training Camp and south of the Gnome Stronghold is an abandoned apple yard. Take a Rotten Apple from 1 of the piles there and take 2 Barrels. Take a scoop of the rotten apple pile with 1 of your barrels, and use it on the Apple Barrel to mush them.

Head back to Elena and show her the single Rotten Apple. She will give you a Sieve afterwards.

 

Making Naphta

Now, you need to make some Naphta. Get some Coal-Tar with your barrel back at the swamp in Isafdar. Talk to the Chemist and then pour the Coal Tar into the Distiller on the Still. Put some Coal inside and the heat will increase. When the heat level turns green, turn the right valve on. If the pressure goes over the green level, turn the left valve on.

 

Don't let the pressure get too low, so be sure to close the valve when it goes below the green level. Do this until the Coal-Tar is distilled (the bar is completely green). Once you have your Naphta, use the Barrel of Naphta on the Barrel of Apple Mush and you will get A Naphta-Apple Mix. Use the Sieve on it and you will get a barrel of Toxic Naphta.

 

Use the Toxic Naphta on a range to heat it (Note: Don't use it with a fire or it will explode!) After you've used it on the range, you will get 2 Toxic Powders. Use them on the grain sacks at the 2 different places marked on the Ardougne Map.

After you have done that, go back to the head mourner, and the quest will be completed!

Rewards
25,000 Hits and Thieving experience.
Full Mourner Set
Strange Bloated Toad Shooting Device (a Bazooka)
Lletya Teleportation Crystal
2 Quest Points