RuneScape Quests: Biohazard

In RuneScape, to complete the quests would make you gain some RuneScape money or other items as reward.
Difficulty level: Medium
Start location: Talk to Elena in the building west of the Northern Bank of Ardougne, across the river.
Monsters: Mourner (level 13)
NPC: Elena, Jerico, Omart, Kilron, Chemist, Chancy, Da Vinci, Hops, Guidor's Wife, Guidor, King Lathas

Walkthrough Steps

1: Elena
She will tell you to talk to Jerico who is in a house just south of Ardougne's north bank. He will tell you to talk to Omart found at the southern wall.

2: Omart
After talking with Elena head over to Omart, who will tell you that you'll have to talk with Jerico about something to distract the guards. Jerico will just send you back to Omart because he's too busy feeding his pigeons. While at Jerico's, search his cupboard to find some pigeon feed, and go around back and take a pigeon cage.

3: Over the wall
Go to the tower next to the West Ardougne city gate and use the pigeon feed on it. Then release the pigeons. Talk with Omart and he'll help get you over the wall. Now go all the way north and take a rotten apple west of the most north-eastern house there. Now go round to the front of the house and try to enter the front door.

4: Doctor
The mourner will tell you that they're all sick, so you'll have to play a doctor now. To do this you'll need a doctor's gown will cost some RS money. Go to Sarah's house in the southwest corner of West Ardougne. Search the box to get the gown. Put it on and go back to the mourner. Open the door to the building and go upstairs, where you'll find a mourner you'll have to kill.

5: Elena's distillator
After you kill the mourner upstairs you'll get a key. Use this on the gate there, and search the crates inside. You'll get Elena's distillator. Now return to where you came over the wall and get Kilron to help you over. Head back to Elena, and she'll tell you to take some samples to the Chemist in Rimmington.

6: Chemist
Once at the Chemist's house a little west of Rimmington, talk with him. Then go outside and give Chancy the liquid honey, Hops the sulphuric broline and Da Vinci the ethanea.

7: Varrock
Go to Varrock and buy a priest robe top and bottom from the Clothes Shop if you haven't done that already. Go to the Dancing Donkey Inn in south-east of the East Varrock Bank and get your samples back from the three men there.Talk with him, and he'll tell you that there is no plague. Go back and give Elena the good news. Then go south to the Castle and upstairs to the throne room to see King Lathas for your RuneScape gold reward.

Reward:

1,250 Thieving exp
Unrestricted use of main gate into West Ardougne
Permission to use King Lathas' training ground north of West Ardougne
Quest points gained on completion: 3