Cappy in a Haystack

Cappy in a Haystack is a quest in the Fallout 4 add-on Nuka-World.

Detailed walkthrough
Between The Parlor and Fizztop Grille, Sierra Petrovita is encountered talking to a raider. Intercepting the conversation reveals that she has come to find the reward for finding hidden Cappys throughout the park. Given that the reward was meeting the creator of Nuka-Cola, she figures that in his office might be the original recipe for the drink. She gives her sunglasses to you before leaving.