The Letter is a quest item in The Golem quest, obtained towards the beginning of the quest after the player has spoken to the Clay golem. It is found lying on the floor in the ruined city of Uzer, in one of the remains of the houses.
The letter details the next step of the quest; journeying to the Digsite near Varrock to find Varmen, and eventually to steal a statuette from Varrock Museum in order to help fix the golem and make it understand that Thammaron is dead, and its task is complete.
I hope this finds you well. Here are the books you asked for. There has been an exciting development closer to home -- another city from the same period has been discovered east of Varrock, and we are starting a huge excavation project here. I don't know if the museum will be able to finance your expedition as well as this one, so I fear your current trip will be the last.
May Saradomin grant you a safe journey home.
Your loving Elissa.
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