Fallout 76 Oldest Trick in the Book quest guide – How to find Cassidy

Oldest Trick in the Book is one of the two-part quests assigned by Audrey Stolz to wipe out the Cultists that have exiled Cassidy, Hugo’s wife, in the Skyline Valley update for Fallout 76.

There are a few parts to this quest, so we’ll go over everything you need to do to complete the mission in Fallout 76.

How to complete the Oldest Trick in the Book quest in Fallout 76

Speak with Hugo Stolz

After completing the Seeking Shelter Skyline Valley quest, speak with Audrey in Dark Hollow Manor to begin this mission. During the conversation, Hugo Stolz asks for your help to find his wife Cassidy. Audrey then tells you the location of Cassidy and assigns you to find her and wipe out the Cultist leader who’s captured her.

Travel to the Old Crimora Mines and wear a disguise

Once the conversation ends, a marker on your map appears, showing the location of the Old Crimora Mines in the southern corner of the map. Travel to the marked location and wipe out all the Cultists roaming the surrounding areas.

Once all the enemies are wiped out, head inside the shed next to the entrance of the mine to find the Cultist Garments you need to wear.

Explore the Old Crimora Mines

Once you’ve donned the disguise, head into the mines and explore. The paths are narrow but straightforward, so you won’t get lost. After reaching the upper portion of the cave, follow your quest marker on the bottom of the HUD to find Elder Pepper, the mine’s guardian.

Elder Pepper blocks your progress until you provide a password. You have the option to shoot him, triggering a shootout with the Cultists, or simply give him the password.

The password is written on a piece of paper located at the end of the cave on the upper level, placed on a bed. Retrieve the password and present it to the guard to access the rest of the cave.

Find Cassidy

With access to the rest of the mine, your quest marker again updates to direct you to find Cassidy. Explore the new area and unlock the prison cells to locate Cassidy; there are four doors to open.

As you search for Cassidy, you can also collect valuable loot, including numerous Black Titanium veins.

Speak with Alex

After finding Cassidy, go to the main area of the mine to talk with Alex, the Cultist leader. She shares her hatred for Hugo and reveals the atrocities he’s committed.

Following the conversation, Alex commands her disciples to attack you. Defeat all the Cultists and then escape the mine to speak with Hugo.

Escape the mine and meet Hugo

Wipe out all of the Cultists until your quest marker tasks you to meet with Hugo. Escape the mine and speak with Hugo at Dark Hollow Manor to complete the Oldest Trick in the Book quest in Fallout 76‘s Skyline Valley update. Finishing the mission rewards you supplies, a good chunk of XP, and a Cultist Monarch Outfit.

How to fix the Oldest Trick in the Books quest bug

There is a serious bug in this quest where, after meeting with Alex and killing all the Cultists, the quest marker doesn’t update and still says to wipe out the Cultists. This happened to me, too, but restarting the game and starting the quest all over again fixed it for me.

If you tried this and the game still doesn’t resolve the Oldest Trick in the Book bug, try changing your server, joining a friend’s server, or canceling the quest in your Pip-Boy and starting it again to see if that works in Fallout 76.