Lock Every Door by Riley Sager

No visitors. No nights away from the apartment. No disturbing the other residents. All of whom are rich or famous or both

These are the only rules for Jules Larsen's new job as an apartment sitter at the Bartholomew, one of Manhattan's most glamorous and secretive buildings. Recently heartbroken and just plain broke, Jules is captivated by the splendor of her surroundings and accepts the terms, ready to leave her past life behind

As she gets to know the residents and staff of the Bartholomew, Jules finds herself drawn to fellow apartment sitter Ingrid, who comfortingly reminds her of her sister who vanished eight years ago. When Ingrid confided that the Bartholomew is not what it seems and that the dark history hidden beneath its gleaming facade is starting to frighten her, Jules brushes it off as a harmless ghost story ... until the next day, when Ingrid disappears

Searching for the truth about Ingrid's disappearance, Jules digs deeper into the Bartholomew's sordid past, and the mysteries kept within its walls. What she discovers pits Jules against the clock as she races to unmask a killer, expose the building's hidden secrets, and escape a dream apartment that has quickly turned into a nightmare