Every night, she cleans. On the fourth floor of an unnamed office in an unnamed city, the night cleaner comes and does what she does best—sorts out the messes of the daytime employees. None of them know her, but she knows everything about them: Sad Intern’s dreams to get promoted, Résumé Woman’s nasty flight-risk behavior, Mr. Buff’s secret smoking habit (not very conducive to his fitness journey). She’s the office mastermind, the one everyone needs, and no one even knows she exists.

And tonight, while scrolling through your emails, she’ll discover the secret you’ve been hiding—the one that will put everyone’s job at risk. After all, protecting the employees is her responsibility: whether it’s from rats and window smudges or from the sinister CEO who may be driving the company into ruin. And you’re about to find out that, sometimes, your most powerful enemy is the one you don’t even see.