Speak with Councillor Halgrive near or inside the chapel just east of the castle bridge in East Ardougne (near the point marked 1 on the map!) Note that the in-game quest diary specifies he is near the Ardougne zoo and this is relatively correct. The chapel is just to the north of said zoo! Halgrive will be wearing blue colored clothing which may help in identifying him. Other NPCs in the area also have a habit of standing on top of him making him sometimes hard to spot!
When you try asking him what's wrong he'll tell you the story of the problems that have recently beset Ardougne.
“You may or may not be aware, but a plague has spread across Western Ardougne. Now, so far, our efforts to contain it have been largely successful, for the most part. However four sheep recently escaped from a farm near the city. When they were found, we noticed that they were strangely discoloured, so we asked the mourners to examine them. They found that the sheep had become infected with the plague. As the councillor responsible for public health and safety here in East Ardougne I am looking for someone to herd these sheep into a safe enclosure, kill them quickly and cleanly and then dispose of the remains hygenically in a special incinerator. Unfortunately nobody wants to risk catching the plague, and I am unable to find someone willing to undertake this mission for me.”
You, of course will choose to take the job.
Halgrive is overjoyed. In the course of the conversation to follow he will give you a bag of Poisoned sheep feed.
When asked as to how you will be able to identify the diseased sheep he will tell you:
“The poor creatures have developed strangely discoloured wool and flesh. You should have no trouble spotting them.”
Your next steps should be:
Found in the nearby chapel, Doctor Orbon is wearing a white lab coat.
When asked about the protective clothing Councillor Halgrive had mentioned he will be a bit taken back. It seems he only has one outfit which he made for himself. He will, however, be glad to sell you that set if he can be paid enough (100 gp) to enable him to make a replacement. Note there is a bank just a bit north of the chapel if you did not bring your 100 gp with you!
Once you have obtained the set put it on.
Note if you have Boots of Lightness your weight will be reduced from that of the image above.
Proceed north of the city via the path to the west of the chapel. There you will find Farmer Brumpty's land which encloses the spot marked as 2 in the map above. You will only need to talk with Farmer Brumpty himself if you attempt to enter his enclosure without wearing your protective clothing.
Now, enter the pen in Farmer Brumpty's enclosure via the gate. Note: If you are not wearing the protective clothing when you attempt to open the gate Farmer Brumpty will stop you saying “You can't enter without your protective gear! Can't have you spreading the plague!”
From there go into the building housing the Incinerator (marked as 2 on the map). In the southeast corner you will find a Cattleprod on the ground. Pick this up. You can either Left-click or Right-click this item (when in your inventory) and Equip the Cattleprod.
Now your task is to herd one (1) sheep of each color (red, green, yellow, and blue) to the gate and into the pen.
To Repeat This Note: You only need to get ONE SHEEP OF EACH COLOR!
When you click to prod a Sick-looking sheep (Note: It is not necessary to right-click! Just clicking on them with the Cattleprod equipped will do) it will be identified by a number in parenthesis. Note: If you attempt to click a sheep without having the Cattleprod equipped you will get the message “You can't prod a sheep with your bare hands.”
This number tells you which of the four (4) sheep you are working on.
Once you get a sheep within range of the Gate (designated by the area on the map) they will auto-magically appear in the pen. The sheep can very quickly walk away, requiring you to re-do your efforts!
Once you see a sheep vanish and re-appear inside the pen it is time for you to proceed to the next step!
I'd strongly suggest that you do not attempt to get all four (4) sheep into the pen at the same time. If a sheep is near the Gate DO NOT OPEN IT! The sheep can quickly escape requiring you to re-capture it!
Note: The bones will be numbered to correspond with which numbered sheep on which you are currently working.
The sheep are sequentially numbered with Red being (1), Green (2), Yellow (3) and Blue (4).
It does not matter in which order they are dealt with!
Once you have completed this series of actions for one of each color of sheep head back to Councillor Halgrive. On speaking with him they congratulate you and reimburses you for the cost (100 gp) of the Protective clothing. In addition he rewards you 3,000 gp in recognition of your service to the public health of Ardougne.
Congratulations! Quest Complete!