Chasing Shadows

Chasing Shadows is a side quest in Fallout 76.

Quick walkthrough

 * Listen to the Order of Mysteries - The Phantom Device holotape.
 * Use Cryptos to access the entry "Novice | Phantom Device Component."
 * Obtain a HalluciGen gas canister from Garrahan Mining Headquarters if not already in possession.
 * Obtain a Stealth Boy from North Cutthroat camp if not already in possession.
 * Use the Fabricator to make the device.

Detailed walkthrough
Chasing Shadows is a subquest of the Novice of Mysteries quest and requires the player character to master the use of the Phantom Device, the Mistress of Mystery's tool for stealth and infiltration. It automatically begins when one begins the Novice of Mysteries quest.

First, listen to the Order of Mysteries - The Phantom Device holotape to hear a description of the device and instructions to search Cryptos for leads on the two main components needed for crafting the device - a HalluciGen gas canister and a Stealth Boy. Access the Cryptos terminal in the basement of Riverside Manor and navigate to the Database Queries – Novice | Phantom Device Components entry. Accessing this entry will update the player character's map with quest markers for the locations of the two main components.

The HalluciGen gas canister is located inside the Garrahan Mining Headquarters. It is in a locked (Picklock 2) safe in the CEO's office, directly across the lobby from the main entrance. The safe can also be opened using the level 0 locked CEO's terminal on the desk. The marked Stealth Boy is located in a locked (Picklock 0) footlocker on a shelf in the North Cutthroat Camp. This footlocker will also contain Jake's letter which is marked as a quest item but is not necessary for completing this quest. While getting the materials, watch out for the hostile enemies at both locations: Robots at the Garrahan Mining Headquarters, and Blood Eagles at the North Cutthroat Camp.

Note: It is not necessary to obtain the items at these marked locations. This step can be skipped if the player character already possesses the necessary crafting components.

Once the player character has obtained the necessary crafting components, they should return to the Riverside Manor basement. Access the Fabricator terminal on the lower level and use it to craft a Phantom Device to complete the quest.