In a dystopian society, a corporation called Lumon Industries offers a controversial procedure known as "severance," which involves surgically splitting employees' memories into separate work and personal lives. Mark, a team leader at Lumon, has undergone this procedure. At work, he has no recollection of his personal life, allowing him to focus solely on his professional responsibilities. Similarly, when outside the office, he remains oblivious to what happens at work. The story follows Mark and his colleagues in the Macrodata Refinement division as they navigate this bizarre double life. As they carry out their mysterious tasks under the watchful eye of their stern supervisor Harmony, cracks begin to appear in the seemingly flawless system.

Initially drawn in by the promise of improving productivity and balancing personal and professional life, Mark eventually grows uneasy about the opaque nature of his job and starts to question the ethics of severance. A series of unsettling events, including the abrupt resignation of a colleague, fuel his skepticism. Simultaneously, he attempts to cope with personal tragedies outside work, which adds to his mounting internal conflict. Notably, the arrival of Helly, a new employee who struggles with her new identity, further complicates matters. As the team members become more aware of the information withheld from them, they start piecing together clues that point to potential dangers lurking within Lumon’s walls. Unable to ignore their suspicions any longer, they cautiously seek to understand what truly lies behind their severed lives.