OSRS Biohazard Quest Guide

Biohazard picks up where Plague City left off, continuing the story as Elena finally gains access to her plague samples. But beneath the surface of her research lies a carefully concealed secret that changes everything.

Difficulty: Easy

Length: Short

General Questing recommendations

• Enable RuneLite Quest Helper in your RuneLite plugin section. 
• Hold your space bar to skip through NPC dialog, and use number keys for chatting dialog.

Quest Requirements for Biohazard

Plague city

Item Requirements for Biohazard

Gas mask

Recommendations for Biohazard

• 3 Ardougne teleports
• 1 Teleport to Rimmington
• 1 Teleport to Varrock: Teleport to house if you have a house in Rimmington is a good option.
• 30 coins

Walkthrough of Biohazard Quest

• Talk to Elena at her house west of the northern Ardougne bank. Reply 1 to start the quest.

• Cross the log east of Elena’s house and talk to Jerico in his house south of the northern Ardougne bank.
• Get bird feed from the cupboard in Jerico’s house by opening and searching it.

• Get a pigeon cage from behind Jerico’s house.
• Investigate the watchtower near the entrance to West Ardougne.

• Open the pigeon cage next to the watchtower.
• Wear a gas mask, talk to Omart, and reply 1 for him to sneak you into West Ardougne.

• Squeeze through the fence to enter the Mourner’s Headquarters yard in the northeast of West Ardougne.
• Pick up the rotten apple in the yard.

• Right-click and use the rotten apple on the cauldron.

• Search the cupboard in Sarah’s house, southwest of the West Ardougne church.

• Enter the Mourners’ Headquarters, northeast of West Ardougne, while wearing the medical gown.

• Go upstairs and kill the mourner in the east room. It is an easy fight, so you don’t need combat gear as long as you have 30+ melee stats.

• Search the crate in the caged area for Elena’s Distillator.

• Return to Elena. You can talk to Kilron at the location you used to enter West Ardougne, so that he can sneak you back out.

• Bring the following items: 1 Plague sample, 1 Liquid honey, 1 Ethenea, 1 Sulphuric broline, and 1 Touch paper.
• Take the Plague Sample to the Chemist in Rimmington. (You can take a boat from Ardougne Dock to Rimmington for 30gp.). Reply 2 to receive touch paper.
• Talk to Hops and reply 3 to give him the Sulphuric Broline.
• Talk to Chancy and reply 2 to give him the Liquid Honey.
• Talk to Da Vinci and reply 1 to give him the Ethenea. All 3 can be found close to the Chemist.

• Go speak to Hops, Da Vinci, and Chancy in the pub in the southeast of Varrock. If you lose any of the chemicals, return to Elena to get more. You will be searched at the entrance by a guard and will be allowed through if you are not with any of the chemicals.

• Talk to Asyff in the eastern building and reply 2 to get a free priest gown. (You can only get the free set once.)
• Wear the Priest gown and talk to Guidor in his house to the south. Reply 1, 
• Talk to Elena.
• Talk to King Lathas to complete the quest. Climb up the stairs in the Ardougne Castle and enter the east room to get to him.

Rewards from Biohazard Quest

• 3 Quest points.
• 1,250 thieving Experience.
• Full West Ardougne Access
• Combat Training Camp Access