A Handy Adventurer
Start by talking to Bert, who will be worried that he's going to lose his job. He will give you the hand and ask you to talk to the Guard Captain. Go across the street and into the bar. Buy a cheap bear from the Bartender.
Talk to the Captain and he will talk to you now when you give him the beer. He drunkenly tells you to talk to the Wizards and see if they know. Ring the bell outside the Wizards' Guild to the east and speak to Zavistic Rarve.
You will hand the hand over, and he will recognize it as Clarence's. He will ask you to talk to Bert about the long hours he's recently been working. He will tell you that he works for Sandy's Sand Corp in Brimhaven. Bert will give you his rota.
Hand it over Sandy
Head to Sandy's office in Brimhaven, just south of the Shrimp & Parrot.
Return to the Guild and ring the bell to talk to Zavistic Rarve again. He will take the scroll, and say it's a mind altering scroll. He will give you a magical scrying orb, and tell you to find Betty in Port Sarim to make a truth serum.
Handful of TruthTalk to him again and ask if he can help you a little more. In exchange for a vial, he will teleport you directly to Betty. Talk to her and she will give her the other vial. She will give you a bottled water. Use red berries on the bottle, then add in white berries to get pink dye. Use the dye on the lantern lens.
Talk to her again, and she will tell you to stand in her doorway and shine it on the vial on her desk. Open the door, and stand in the doorway (on the inside of the building) and use the lens on the potion. She will give you the truth serum.
Talk to her again to learn the final ingredient. Head back to Sandy and try to pick his pocket. It make take several attempts, but you will eventually get a little bit of sand. Return to Betty.
She will mix it in and complete the potion. Return to Sandy once more. Talk to him and tell him that the pygmy shrews have eaten all of the sand, then put the serum in his mug on the table next to him.
He will drink it. Activate the magical orb and start talking to him. Ask him each of the questions. You will learn all you need to know.
Return to Zavistic Rarve. He will watch the recording, then asks for 5 earth runes and a bucket of sand. He will magically fill up Bert's sand pit so he doesn't have to do anymore work.
He will ask you to check the Entrana sandpit.
At the pit, talk to Mazion. He will give you, of all things, a head! He will be glad to get rid of it. Return once more to the Wizards' Guild and talk to Zavistic again. You will hand him the head.