Speak to Halgrive. He will say that he is concerned about some plagued sheep and would like you to get rid of them by poisoning them and incinerating them in a special area they set up by Farmer Brumty. He will give you some poisoned sheep feed, and then tell you to pick up a Plague jacket and Plague trousers from Doctor Orbon.
Head inside the church and talk to Doctor Orbon, who will ask for 100 coins in return for the suit.
Head to the incinerator just northwest of the northern entrance to Ardougne. Enter the fenced enclosure using the gate on the west side.
Take the cattleprod lying on the ground near the incinerator.
Now you can begin to dispose of the Sick-looking sheep by wielding the prod and then using it to direct the sheep into the pen around the barn. You only need one of each colour (in any order), and you can finish one sheep at a time. For each sheep, once you have directed them to the gate of the incinerator complex, give them some poisoned food to kill them and then use their bones on the incinerator.
The first sheep is located by the north entrance to the city. It is red.
Once all of the bones have been incinerated, head back to Halgrive and claim your reward of 3000 coins (and expenses of 100 coins) and you are done with the quest.
Speak to Councillor Halgrive outside of the Ardougne church.
