An ace police force crisis negotiant, Chae-yoon, is name to the scene where her supervisor is take surety. Through the control room proctor, she is confront with the cold surety taker, Tae-gu, whose demeanor are hard to construe. Against the 21-hour deadline Tae-gu has set, Chae-yoon indefatigably try to check the remarkably unagitated perp over multiple video-calls. finally, the shock truth get down to unveil.