A twist-filled psychological thriller by Freida McFadden that explores office politics, hidden identities, and the dangerous consequences of bullying and deception.

The story revolves around two coworkers at a nutritional supplement company. Dawn Schiff is an awkward, socially isolated accountant who follows an obsessive routine and is considered strange by everyone in the office. Natalie Farrell, on the other hand, is the company's charismatic and successful top salesperson, admired by nearly everyone.

When Dawn unexpectedly fails to arrive at work one morning—a shocking break from her rigid routine—Natalie receives a mysterious anonymous phone call that pulls her into a disturbing investigation. As the search for Dawn unfolds, long-buried secrets, workplace rivalries, manipulation, and hidden motives begin to surface. With every chapter, the reader's assumptions are challenged, leading to a series of unexpected twists that blur the line between victim and villain.

Written in McFadden's signature style of short chapters, cliffhangers, and unreliable narrators, The Coworker is a fast-paced thriller that examines appearance versus reality, workplace toxicity, and revenge.