In the glittering, high-stakes world of Seoul's elite, Kang Min-seo, a talented but struggling graphic designer, agrees to a desperate plea from her best friend, Ji-hoon. Her mission: pose as his perfect, devoted girlfriend to fend off his family's relentless matchmaking. It's a simple, foolproof plan—a temporary charade for one night.

But their little deception spirals into a full-blown performance when she meets Ji-hoon's older brother, Kim Min-joon, a quiet, perceptive CEO who sees through their act from the moment she walks through the door. Caught, Min-seo strikes a new deal, agreeing to become Min-joon's fake date to a corporate gala in exchange for his silence.

What begins as a cold, calculated transaction between two co-conspirators soon becomes a series of late-night conversations and stolen glances. As their fake romance deepens, Min-seo finds herself falling for the guarded CEO, and Min-joon discovers a world beyond logic and reason—a world with a heartbeat.

Now, with their lies unraveling and the truth threatening to expose them all, Min-seo and Min-joon must decide if the beautiful, honest love they've found is worth risking everything for. Can a relationship born from a lie survive its own truth, or will their Christmas charade end in a final, heartbreaking goodbye?