OSRS Biohazard Guide

02.03.2024 - 17:25:03
Game Guides , Runescape

OSRS Biohazard Guide

Plague City isn't the last of one of the longest stories in OSRS. Once the dust has settled, the story continues with a new quest called Biohazard. If you're about to do this quest, here's a quick guide to help you through this short affair easily and quickly.


OSRS Biohazard Preparation

Before anything else, here's a short list of all of the things you need to start Biohazard,

Quest Requirements:

  • Plague City

Items Required:

  • Bird feed: Acquireable during the quest, located in a cupboard within Jerico's residence.
  • Pigeon cage: Obtainable during the quest, situated behind Jerico's house.
  • Priest gown (top and bottom): Available during the quest at Asyff's Fancy Clothes Store for a combined cost of 12 coins.
  • Gas mask: Obtainable at no cost from the cupboard within Edmond and Alrena's house in East Ardougne.


  • Combat Level 10
  • Stamina or Energy Potions
  • Fast Travel Options to Various Locations:
    • Rimmington (Rimmington teleport, Teleport to House if your house is in Rimmington, Explorer's Ring 2, Skills necklace to the Crafting Guild, or Rat Pits minigame teleport)
    • Varrock (Varrock teleport, Chronicle, or Combat bracelet to the Champions' Guild)
    • Ardougne (Ardougne teleport)
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Biohazard Walkthrough

On this part of the guide, we'll now take you through the in-depth steps you need to take to finish this short quest.

  1. Speak to Elena in East Ardougne, directly west of the shortcut log.
  2. Visit Jerico in the house just south of the northern Ardougne bank. Search the cupboard to obtain bird feed.
  3. Grab a pigeon cage from the backyard (grab an extra 5 if planning to do One Small Favour).
  4. Speak to Omart southwest of Ardougne Castle.
  5. Head north to the small watchtower along the wall in front of the gates to West Ardougne.
  6. Stand in the corner where the two spiked fences meet. Use bird feed on the watchtower fence. Open the pigeon cage in your inventory and equip your gas mask.
  7. Run south from the watchtower and speak to Omart. After a slight delay, you will arrive in West Ardougne.
  8. Head northeast of West Ardougne to find the Mourner HQ.
  9. Navigate to the northeastern area with the vat and mangle.
  10. Squeeze through the fence into the backyard.
  11. Pick up the rotten apple and use it on the cauldron.
  12. Return through the fence.
  13. Go to Nurse Sarah's house, southwest of the West Ardougne church.
  14. Search the cupboard in the northern part of the house for a medical gown. Equip it.
  15. Return to the headquarters, open the door, and go upstairs to kill a mourner. A key will be placed in your inventory.
  16. Use the key on the gate to access the caged room.
  17. Search the crates to find Elena's distillator (in the northeastern single crate).
  18. With 3 empty inventory spaces, return to Elena and give her the distillator.
  19. Go to the Chemist in southwestern Rimmington. Speak to him. He will give you the touch paper.
  20. Find Chancy, Da Vinci, and Hops around a fire outside the Chemist's house.
  21. Give Chancy the Liquid honey, Da Vinci the Ethenea, and Hops the Sulphuric broline.
  22. Teleport or travel to Varrock.
  23. Head to the fenced area southeast of the Varrock bank.
  24. Speak to Asyff in the building south-east to obtain a priest gown top and bottom (optional).
  25. Go to the Dancing Donkey Inn and talk to Hops, Da Vinci, and Chancy to get the vials back.
  26. With your Priest gown equipped, head to Guidor's house in the southeast of the fenced area and speak to him.
  27. Return to Ardougne and speak to Elena.
  28. Go to the 2nd floor of Ardougne Castle and speak to King Lathas.

Starting Out

To start Biohazard, engage in conversation with Elena in East Ardougne, located directly west of the shortcut log. She recommends consulting Jerico, a friend of her father's, who maintains communication with West Ardougne through his pigeons.

Sneaking Back

Items required: Pigeon cage, bird feed, Gas Mask

To begin, approach Jerico, who resides in a house just south of the northern bank of East Ardougne and north of the chapel. Investigate the first cupboard along the north wall of his house to retrieve the necessary bird feed. Then, head behind the house to collect a Pigeon cage.

Note: If you plan on undertaking One Small Favour, it's recommended to gather and store an extra 5 pigeon cages, although it's not mandatory as they're relatively close to the quest objective.

Locate Omart west of Ceril Carnillean's residence in East Ardougne, just south-west of the castle. During your conversation with him, he'll express concern about the risk of crossing the wall due to the nearby watchtower guards.

To divert the guards' attention, proceed to the small watchtower along the wall, directly north of Omart. Position yourself in the corner where the two spiked fences meet, place the bird feed on either fence, then use the cage from your inventory.

Return to Omart, who will call upon his assistant, Kilron, to throw over a rope ladder. Climb over the ladder into West Ardougne (ensure you have the gas mask equipped to continue with the storyline).

Getting Inside Mourner HQ

Recommendation: Make sure to have combat level 13 for the Mourner fight.

Head to the Mourners' headquarters situated in the northeast corner of the city. Attempt to enter, but you'll be denied access as the mourners are engrossed in eating their stew. Your task is to distract them. Move around the headquarters to the northern section, where a cauldron is being tended to in the backyard. Slip through a gap in the fence to enter the backyard and pick up the rotten apple lying to the east.


With the rotten apple in your possession, right-click on it and use it on the stew brewing in the cauldron. Slip back through the fence and circle around to the front of the building. Try to enter again. This time, one of the mourners will inform you that entry is prohibited due to several mourners being ill with food poisoning and awaiting a doctor.

Next, head to Nurse Sarah's house, the sizable building southwest of the West Ardougne church. Search the cupboard in the northern part of her house to acquire a medical gown. Equip the gown and return to the headquarters. The professional attire will easily deceive the mourners into allowing you inside their base. Throughout the quest, remember to wear the gown for all subsequent visits to the headquarters.

Once inside, proceed upstairs and eliminate a mourner. A key will automatically be placed in your inventory. Use this key on the gate to access the caged room. Search the crates within to locate Elena's distillator.

For Skillers: After conversing with the mourner, he will initiate combat. Utilize a ring of recoil to swiftly defeat him, and the key will appear in your inventory without needing to inflict any damage.

Return to Elena by descending down the manhole in the city center and scaling the mud pile. Alternatively, head back to Kilron at the southeastern corner of West Ardougne, who will assist you in returning to East Ardougne.

A Task For The Chemist

Items required: Falador teleport or amulet of glory (optional), brown apron (optional), or House teleport if your house is located in Rimmington

After conversing with Elena and obtaining the Liquid honey, ethenea, sulphuric broline, and the plague sample from her, proceed to Rimmington via teleportation. It's important to note that the chemicals and plague sample will no longer be deleted. To reach Rimmington, you can teleport to Falador or Draynor Village, head to the cabbage patch, or utilize the single southeastern dock in Ardougne and pay 30gp to Captain Barnaby for direct transportation to Rimmington.

Make your way to the Chemist located in the southwestern corner of Rimmington.

Upon arrival, the Chemist will provide you with the touch paper necessary to advance the quest.

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Smuggling Time

Items required: Liquid honey, ethenea, sulphuric broline, and the plague sample.

The chemist informs you that the Varrock guards are on the lookout for anyone carrying suspicious materials. He suggests utilizing his three errand runners to smuggle the items into Varrock.

Chancy the gambler, Da Vinci the artist, and Hops the drinker are gathered outside the chemist's house, near a fire. Speak to each of them to give them their respective vials. If you mistakenly give the wrong vial to someone, distribute the remaining vials to the others. Then, engage with them all in Varrock before returning to Elena for new vials before retrying this step.

Here's the breakdown of which helper should receive which sample vial and the reasoning behind it:

  • Da Vinci: Give him the ethenea sample vial. Ethenea cannot be used by Da Vinci to create a "work of art."
  • Chancy: Hand over the liquid honey sample vial. Due to its low value, Chancy cannot wager the liquid honey in a gamble.
  • Hops: Provide him with the sulphuric broline sample vial. Hops will refuse to drink it due to its poisonous nature.

A Dangerous Task

Items required: 12 coins or a priest gown top and bottom, the plague sample, and touch paper.

Begin by heading to Varrock and equipping a priest gown set. You can purchase one from Thessalia's Fine Clothes for 10 coins or from the Fancy Dress Shop owner north of Guidor for 12 coins. Alternatively, speak to the Fancy Dress Shop owner to receive an old priest gown that isn't suitable for sale, especially handy after obtaining the vials again.

Proceed to the fenced area in the southeast part of Varrock. As you attempt to pass through the gate, the guard will conduct a search. Be aware that the guard will confiscate the vials if you try to bring them through, but the plague sample is safe to carry.

Now, make your way to the Dancing Donkey Inn inside the gated area, carrying only the plague sample. Speak to Hops, Da Vinci, and Chancy to retrieve the vials. If your inventory is full, you'll need to obtain a new set from the chemist.

Warning: Avoid passing back through the gate at this stage, as your vials will be confiscated upon return!

If you've forgotten to bring the plague sample or touch paper with you, head to Varrock east bank to retrieve them. Drop the vials at the gate, swiftly run to Varrock east bank for the items, and hurry back to collect the vials.

Note that Telekinetic Grab no longer functions to retrieve the contents. Ensure you have both priest gown items before entering to avoid complications.

Finalizing The Quest

Items required: The plague sample, touch paper, a priest gown.

If you've forgotten your priest gown, don't fret. You can obtain one for free by speaking to Asyff in the Fancy Clothes Store. Once equipped, head to Guidor's house situated in the southeast corner of the gated area. Engage in conversation with Guidor to hand over the vials and sample. Inform him that Elena has sent a sample requiring processing. Upon analysis, Guidor will come to a startling revelation: the plague is nothing but a falsehood.

Return to Ardougne and confer with Elena. Upon learning that Guidor's results yielded nothing, Elena suggests that the plague might indeed be a hoax. She advises you to speak to the individual responsible - King Lathas of East Ardougne. You can find King Lathas just south of Elena's house, in his throne room on the second floor of the East Ardougne Castle.

Upon informing the King that the plague is a sham, he reveals his motivations, claiming it was done for the welfare of his people. According to him, it safeguards them from a "far greater danger." He then divulges the tale of King Tyras, his brother and ruler of West Ardougne, who journeyed west and became corrupted by a dark lord after imbibing from the Chalice of Eternity. Thus, the wall separating the cities serves to protect East Ardougne, and by extension, all of RuneScape.

Biohazard Reward

The quest will allow you to proceed with the Elf questline. By finishing this, you'll be able to proceed with the following quests as well:

  • Recipe for Disaster: Freeing the Lumbridge Guide
  • Underground Pass
  • Ardougne Diary (Easy)

As for the rewards, you're going to get:

  • 3 Quest Points: Adding to your adventurer's accomplishments.
  • 1,250 Thieving Experience: Enhancing your skill in the art of thievery.
  • Use of the Combat Training Camp: Located north of the city, you gain access to this facility. Here, you can engage with six training dummies, each yielding 50 attack experience.
  • Freedom to Travel through the West Ardougne Gate: You can now pass through this gate without hindrance.
  • Access to the West Ardougne Teleport: You unlock the West Ardougne Teleport spell within the Arceuus spellbook, as well as the corresponding teletab, facilitating swift travel to this location.

One More Quest Down

Finishing Biohazard will ultimately lead to Song of the Elves. As one of the longest and most rewarding questlines in the game, finishing Biohazard is definitely going to be worth the trouble.

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