Going Dark by Melissa de la Cruz

 Josh and Amelia are a young college age couple who are on a European vacation. On the day they are set  to return to San Diego, CA, Amelia starts a fight with Josh and walks away. Josh returns to the US without Amelia as she never gets onto the flight. Upon arriving he discovers that no one else has heard from Amelia and that her socials have gone dark despite being an active media influencer.

Tori a friend of Amelia is suspicious of Josh and reaches out to Harper Delgado a well known hacker. Harper is not initially interested but as time passes she becomes emotionally invested and starts looking into both Josh & Amelia. The more she uncovers the more interesting the book becomes. 

The story is told via flashbacks,  multiple points of view and social media posts. Be prepared for a fast ride that will keep you turning the pages untilt he week hours of the night.