In this OSRS Biohazard Quest Guide, we’ll go through all the steps to complete the quest.
This guide is a part of our OSRS Optimal Quest Guide.
Biohazard story & info
Storyline
Biohazard follows up with the Plague City story. The rescued Elena needs your help. Her distillator is still in West Ardougne and she needs it to figure out how she can solve the Plague and rescue the people of West Ardougne. During this quest, you will once again infiltrate West Ardougne, poison some Mourners, enter their headquarters as a doctor, kill one of their men, to find Elena’s distillator.
But the quest doesn’t end there. She discovers there is something wrong… The Plague seems to be fake, and you need to help smuggle the results to her teacher in Varrock for a second opinion.
Info
This quest follows up with the Plague City Quest line.
After the quest, you can freely access West Ardougne.
Quest Requirements
Skill Requirements
There are no skill requirements.
However, you must be able to kill a level 13 Mourner.
Quest Requirements
Item Requirements
- The only item you need is the gasmask from Plague City.
Recommendations
- Teleports to Ardougne
- Teleport to Rimmington
Biohazard Guide
Quest Start
Speak with Elena in her house (next to her father’s house from Plague City) to start the quest.

She wants to figure out how to stop the plague and needs her distillator. You agree to go back to West Ardougne to fetch it for her.
However, the tunnel we used for Plague City has been filled up. She tells you Jerico can help.
1. Sneaking into West Ardougne
Jerico is located next to the Northern Ardougne bank.

Speak with him. Then open the cupboard in his house to find some bird feed.
Next, pick up a pigeon cage from behind his house.

Now go to the gate to West Ardougne and investigate the watchtower.

Then, open the pigeon cage in your inventory to distract the guards.

Now run South and locate Omart on the corner of the wall.
Equip your gasmask and speak with him.

Omart will help you climb over the wall.
2. Infiltrating the mourners HQ
Once inside West Ardougne, run to the big house in the northeastern corner.
Squeeze through the fence in the back.

Pick up the rotten apple in the yard and use it on the cauldron.

Now run to the house in the southwestern corner.

Search the cupboard to find the Doctors gown. Equip it.

Now return to the Mourners Headquarters, this time through the front. You are a doctor after all.

Go upstairs and kill the Lvl 13 Mourner. He will drop a key.

Search the highlighted crate to find Elena’s Distillator.

Now return the Disttilators to Elena. You can teleport to Ardougne or go back toward the wall where you climbed over.

3. Smuggling the vials
Teleport to Rimmington (use home teleport if your house is located in Rimmington) OR you can take the boat from Ardougne to Rimmington for 30 GP.
Speak with the chemist, just west of the house portal.

Now go outside and give your vials to the three lads for them to smuggle inside Varrock.
First, speak with Hops and give him Sulpheric Broline. (option #3)

Then, speak with Chancy and give him Liquid Honey. (option #2)

And finally, speak with Da Vinci and give him Ethenea. (option #1)

Now teleport to Varrock.
Go to the southeastern pub as highlighted below.

Speak with Hops, Da Vinci, and Chancy to acquire your vials.

Once you have spoken to all three men and acquired your vials, speak with Assyf in the clothes shop.
Ask him for a Priest Gown.

Equip both pieces of the Priest Gown.
Now speak with Guidor in the southeastern house.

And guess what? The Plague is fake!
4. Relay the interesting news
Now return to Elena in West Ardougne to tell her the interesting news.

Now finally, speak with King Lathas in his castle and tell him the Plague is a hoax.

And your quest is complete!
Quest Rewards

- 3 Quest Points
- 1,250 Thieving Exp
- Full access to West Ardougne
- Access to the Combat Training Camp
Biohazard Quick Quest Guide
If you prefer video footage, check out Slayermusiq’s Quick Guide on Biohazard.