Seou always knew that running away from the son of a murderer would eventually haunt her, but she never expected to be locked underground with him. Years after she abandoned Wonhyeok following a bloody secret on some stairs, a twist of fate traps them together in the suffocating darkness of an abandoned bunker. As the heavy door clicks shut, Seou must decide if the boy she betrayed is here to finally protect her, or if he’s been waiting all these years to exact his revenge.