Sohee is a high school student excited to land an externship at a major internet provider's call center, but the prized office job turns out to be a nightmarish workplace. The pressure of the job eventually leads to her death. Detective Oh Yoo-jin (Bae Doona, SENSE8, THE HOST) retraces Sohee's steps to reveal the cause of her death. Yoo-jin finds out that the incident's hidden side is more insidious than she ever could have imagined.