A Reason

Ji-soo (Lee Bo-hee) is a professor of mathematics at a university. Her husband has been in a vegetative state for decades because of a car accident. Ji-soo does not have any joy in her life. On her husband's birthday, Ji-soo meets Song-yi (Greena Park). Ji-soo came as a caregiver for Ji-soo's husband. Since then, Ji-soo's life begins to change.