Detective Case Files

Detective Case Files is a quest in Fallout 4.

Quick walkthrough

 * Head to Nick Valentine's Detective Agency.
 * Talk to Ellie Perkins.
 * Accept her request in solving some cases.
 * One will acquire the Earl Sterling Case File and the Marty Bullfinch’s Holotape. Picking up the former will start the side quest "The Disappearing Act", while listening to the latter will start "The Gilded Grasshopper."