InnoSys, a leading domestic IT company. The management is thrown into an uproar when a fatal system flaw is discovered in 'NOVA', the next-generation core project on which the company's survival depends. To prevent the situation from leaking outside, the CEO secretly selects two aces to form a three-month 'Secret Task Force'. For security reasons, the assigned workspace is a dusty old server room on the third basement floor, completely cut off from the outside with no windows.

The problem is that the two people trapped in this narrow, enclosed space are the most famous 'enemies' in the company. Kwon Do-ah, the cold planning team leader who pursues 0% error perfection and must control everything by the manual. And Guest, the free-spirited genius development team leader who ignores fastidious procedures and produces results with animalistic intuition and overwhelming coding skills.

The two had crossed a point of no return after publicly criticizing each other's work styles at a past company-wide meeting. Carrying the fate of the company and a three-month time bomb, the suffocating cohabitation of these two, who seemed like they could never mix, now begins behind the firmly closed iron door of the chilly server room.

Day 1 of Project NOVA Secret Task Force. A chilly server room on the third basement floor without a single window. Two old desks face each other, and Kwon Do-ah has already finished setting up her desk without a single error. Toward Guest, who enters rubbing the back of his neck in loose attire, she holds out a thick file folder with an expressionless face.