Buyers and Cellars

Starting off
To start the quest, speak to Darren Lightfinger in his cellar. Proceed through the dialogue until a prompt to start the quest shows up, then choose to start it. Darren will ask you to pickpocket the dummy; once you've done so, he will explain that he needs money for the Thieves' Guild. He mentions the Golden chalice and asks you to find Chief Thief Robin for further instructions.

Getting the Chalice
Go to the Lumbridge Castle courtyard and speak to Robin, who is lurking at the south wall. He says that Father Urhney has retrieved the chalice from the bank, so you have to get it from his house instead. Go to his house in Lumbridge Swamp and ask about the chalice. He says that he won't let you touch it.

Go back to Robin, and he will give you a tinderbox to make a fire under one of the windows. There are logs on the top floor of Lumbridge Castle. With your tools, go back to Father Urhney's house, and make a fire close to one of the windows.

Talk to him and mention the chalice, but then shout, "Fire! Fire!" He then worries about his house that he "built with his own two hands" - do not click continue but right click Father Urhey and pickpocket him get a Complex key.

Note: You'll need to be quick. If he says, "Accursed kids,..." it is too late and you'll need to speak to him again - possibly after lighting a fire again if it's gone out - to trigger the "Fire! Fire!" option.

Finishing up
Go to the display case and open it using the key to get the chalice. After you give the chalice to Darren, you are recognised as an official guild member. Congratulations, Quest Complete!

Rewards

 * 1 Quest Point
 * Access to the Thieves' Guild
 * Ability to develop the Thieves' Guild by completing the Capers miniquest
 * 3 Thieves' guild pamphlet (each granting 175 Thieving experience for a total of 525 experience)
 * You can pickpocket the dummy a few times within the guild to gain an additional 2,000 Thieving experience

Music

 * Thieves' Guild I
 * Thieves' Guild II (While going back in guild after the quest)
 * Thieves' Guild III (While going back in guild after completing 2 miniquests after the quest)
 * Thieves' Guild IV (While going back after finishing all parts)

Capers
After completing the quest, you gain the ability to expand the Thieves' guild by completing the Capers miniquest. There are a total of three, all requiring different levels. They are:
 * From Tiny Acorns (level 24 Thieving)
 * Lost Her Marbles (level 41 Thieving)
 * A Guild of Our Own (level 62 Thieving, 40 Agility and 46 Herblore)

Trivia

 * On the day of release, the quest was not released with the original system update, a second update about 20 minutes later fixed this.
 * On the day of release, the spoiler in the knowledge base was concealed by "He may not be the most subtle of rogues, but Darren Lightfinger knows how to keep a secret. He's staying tight-lipped about rewards for the time being."
 * If you click on the quest in an adventurer's log, you will be sent to a page in the knowledge base called "Humble roots", which doesn't exist. This could be an earlier name of the quest, a serious typo, or the name of a yet-to-be-released quest.
 * If your Thieving level is fairly high when you are told to pickpocket the dummy, Lightfingers will be amazed and you can teach him for 2,000 more Thieving experience (plus whatever you earn from pickpocketing the dummy.)
 * When exiting the cellar, the building and other buildings associated with this quest have a cyan-coloured box around them when the quest is set as your objective. This effect is toggled off if you clear the objective and can be toggled back on by setting it as your objective again. This is the first time the box has been used for a member's only quest.
 * Along with this update came a glitch in Lowe's Archery Emporium where the posters at the wall would disappear revealing a + and a - sign.
 * There is a glitch when you ask Darren Lightfinger to try the test dummy after picking it, telling him "Let's get down to business" will have him explain you still need to steal the chalice, even after the quest and all capers are accomplished.
 * On the day the quest was released, there was a glitch where when you try to pickpocket "Dummy 1" it would say "I need permission to use this." This has not been fixed.
 * Upon completion of the third miniquest, some players experienced problems with their minimaps. Some players also reported that their browser would freeze.
 * If another player has a fire lit outside, you don't have to use logs, just grab his gloves and then say "nice chalice" and "fire! fire!", and you will be able to steal the key. On the day the quest was released, a large amount of fires were already going outside the house thus many players could skip the entire log option.
 * If you click on the quest list and click the quest before you have done it, a new quest interface will pop up telling you the start point, start requirements, required items, if there's any combat involved, and the rewards. This is possibly a new quest interface for the future. It is so far only used in the low level free play quests, and may be integrated into low level members quests.
 * With the release of this quest players no longer needed to have completed all quests to earn the Helmet of Trials.Questappearfirst.png


 * If you try to use the golden chalice on Father Urhney, the chat box displays "No, that would be a terrible idea."
 * This is the first quest with a quest overview since the hidden update that revamped some older quests such as Cook's Assistant and Vampire Slayer.


 * Strangely, the quest overview is the left click option for this quest.