When a high-stakes architectural project puts sworn rivals Lee Eun-ji and Kang Tae-joon back in each other's orbit, one impulsive photo under the mistletoe ignites a scandal neither can escape. Forced into a fake engagement to win the deal of their careers, every public smile hides a private war—and every staged touch blurs the line between hate and something far more dangerous. This Christmas, love and rivalry will collide under Seoul's glittering lights, and only one can win.