Holy Grail/Quick guide

Royal Hunt

 * Talk to King Arthur in Camelot Castle.
 * Go to the first floor and talk to Merlin.

The Fisher King

 * Go to Entrana.
 * Speak to the high priest, who is in the main chapel of the church.

An Other Realm

 * Talk to Sir Galahad, located in a building west of Seers' Village and east of the coal trucks.
 * Head to the top-most floor of Draynor Manor and into the southern room.
 * Pick up the two magic whistles on the table.
 * Prepare yourself for a level 28 fight.
 * Go to Brimhaven and blow the whistle at the location marked on the map.

Black Guardian

 * Go north-west and defeat the guardian with Excalibur.
 * Talk to the fisherman by the river.

Heirloom

 * Go west, to the castle. Take the grail bell on the floor and ring it.
 * Head upstairs and speak to the Fisher King. Make sure to ask him about his son.
 * Talk to King Arthur in Camelot Castle.
 * Head into the east house of the Goblin village and open the sacks to find Sir Percival.
 * Return to the Fisher King's castle in his realm.
 * Go up the staircase on the other side of the castle, climbing all the way up and grab the Holy grail.
 * Go back to King Arthur.

Quest complete!