Instructions
Talk with the guild master located at the Champion's Guild after you have received the Dragon Slayer quest from Oziach, and he will tell you what happened to each piece of the map. The first piece is located in the maze north of Rimmington, the second is buried with Thalzar and the final piece was stolen by goblin raiders.
Travel to the maze north of Rimmington and use the key the guild master gave you to unlock the gate. Fight off all of the rats in the first room until they drop a red key. Use the key to unlock the red door and continue to the next room.
Battle the creatures you find in each room of the maze until they drop the color key you need to enter into the next room. You will need to acquire the orange, yellow, blue, magenta and green keys before you can enter the room with the first piece of the map. Return to the Champion's Guild to replenish supplies once you have acquired the map piece.
Travel to the Ice Mountain and speak with the oracle, who will tell you the second piece of the map is located in the dwarven mines of Falador. You will need a Wizard's Mind Bomb, a piece of silk, a lobster pot and an unfired bowl to retrieve the map piece. Collect these items from the shops around the guild and then head for Falador.
Enter the mine and take the southeastern path and you will come across a magic door. Use the supplies you brought to concoct a magic spell to open the door. Inside you will find a chest containing the second piece of the map.
Leave the mine and head toward the jail located in Port Sarim. A goblin who has the last piece of the map sits inside the jail, and you can either kill him to obtain the map or bribe the guard with 10,000 gold pieces to retrieve the map. Once you have the final piece, assemble the map in your inventory and proceed to Candor Island.