Here's a quest guide for Undetected Infiltration in Genshin Impact. See how to unlock the quest, a full walkthrough, rewards, and a troubleshooting guide to why Undetected Infiltration isn't working.

How to Unlock Undetected Infiltration

Undetected Infiltration Unlock Guide

1. Complete the "Surreptitious" quest first
2. Defeat the Treasure Hoarders near Glaze Peak
3. Finish the cutscene to unlock the quest

Why is Undetected Infiltration not working?

Complete the Surreptitious Quest to Fix the Undetected Infiltration Bug

Try completing the full "Surreptitious Seven-Star Seal Sundering" quest before going back to defeat the Treasure Hoarders at the quest location.

Undetected Infiltration Quest Guide

Step-by-Step Walkthrough

	Objectives
1	When you get to the old house, there will be a Treasure Hoarder Pugilist, a Hydro Potioneer, two Scouts and a Treasure Hoarder Handyman that you have to defeat to trigger the cutscene.
2	These Treasure Hoarders will turn out to be Millelith in disguise, and their leader, Yanbo, will ask to meet up at Lumberpick Valley, right beside the Teleport Waypoint there.
3	Once you get to the quest location, Yanbo will ask you to pick from three nearby Treasure Hoarder camps. The one you pick will be the one they will attack, leaving you to clean out the other two. You can go to either camp first.
4	The Cooking Quarters will have an Electro Potioneer, Seaman, Handyman and a Treasure Hoarder Crusher. The Alchemy Camp will have 2 Electro Potioneers and 2 Hydro Potioneers, while the Weapons Stash will have an Electro Potioneer, 2 Marksmen and a Seaman.
5	Once you've cleaned out all the camps, you will be tasked to go to the larger Treasure Hoarder camp. There you will be met with waves of Treasure Hoarder enemies. Wave 1 - 1 Cryo Cicin Mage, 1 Pyro Fatui Agent, 1 Treasure Hoarder Crusher Wave 2 - 4 Treasure Hoarder Scouts Wave 3 - 4 Treasure Hoarder Scouts Wave 4 - 2 Pugilists, 2 Crushers Wave 5 - Brass Bull Zhao (Leader) Wave 6 - Chen the Flower (Leader)
6	After defeating all the enemies in the larger camp, a cutscene with Yanbo will be triggered and this will end the quest. This will also earn you an achievement!
7	After the cutscene, you can find a Precious Chest in the middle of the camp! This chest contains the Cup of Commons that you need for the Millennial Mountains quest!

Quest Tips and Tricks

Bring a Pyro DPS

One of your enemies will be a Cryo Cicin Mage, so it's important to bring a Pyro Character as a DPS in your party to bring it down swiftly!

Recommended Pyro Characters
Diluc	Klee	Xiangling	Xinyan
Hu Tao	Yanfei	Yoimiya

Bring Supports with AoEs

Since you will be fighting several groups of Treasure Hoarders, characters that can provide AoE damage are best for Support and Sub-DPS roles in your party. Characters like Venti or Sucrose are especially useful in gathering the enemies together!

Recommended Support Characters
Traveler (Anemo)	Kaeya	Venti	Fischl
Sucrose	Zhongli	Ganyu	Albedo
Yae Miko	Kazuha	Raiden

Undetected Infiltration Rewards

What to Do with the Undetected Infiltration Reward

The Undetected Infiltration quest rewards you with the "Cup of Commons". It's an item you need for completing the Millennial Mountains quest.

Other Quest Rewards

Rewards
Adventure EXP ×250	Primogem ×30	Mora ×30000
Hero's Wit ×3

Additional Undetected Infiltration Info

Undetected Infiltration

The Treasure Hoarders who were behaving oddly turned out to be Millelith in disguise. In response to the resultant situation, their leader asks for your aid in taking out the Treasure Hoarder Camps...

Undetected Infiltration Objectives

Undetected Infiltration Achievement

Achievement	Rank	Primogem Reward
Well Done, Stierlitz!	★	5 Primogems
Objective : Help Yanbo complete the Millelith's mission

Get the Well Done, Stierlitz! achievement after completing the Undetected Infiltration quest!

Genshin Impact Related Guides

All Quests and Quest Types

All The Chasm World Quests Guide

List of World Quests