The Disappearing Act

The Disappearing Act is a quest in Fallout 4.

Quick walkthrough

 * Accept the quest from Nick Valentine's office
 * Search Earl Sterling's house for clues
 * (Optional) Obtain the key to Earl Sterling's house (Vadim Bobrov was his friend and will give it)
 * Investigate the Mega surgery center
 * Obtain the key to the surgery cellar (obtainable from Doctor Sun if a Charisma check is passed)
 * Investigate the surgery cellar
 * Talk to Ellie Perkins

Detailed walkthrough
The quest starts after Unlikely Valentine has been finished.
 * Pick the Novice level lock to Earl Sterling's house or head to the Dugout Inn and speak to Vadim Bobrov to obtain the key.
 * Next go to Earl Sterling's house and look on the floor to the left of the sofa and pick up "Surgery Receipt"
 * Speak to Doctor Sun next to the Mega Surgery Center. There are two ways of getting into the cellar: Examine the blood stain and pass two medium and one hard speech check or pick the advanced lock into the cellar
 * After going into the cellar talk to Doc Crocker, you can either end the conflict peacefully, Arrest him, or kill him.
 * Talk to Doctor Sun
 * Go back to Valentine Detective Agency and collect the approximately 200 Bottle Cap reward.

Journal entries

 * At the ending: I discovered what happened to Earl - Doc Crocker killed him during a botched surgery. I need to let Ellie know what happened.
 * Finished: I told Ellie what I'd found - Doctor Crocker killed Earl and Now he's out of the picture as well. She said she'd break the news to the folks at the Dugout Inn.