Hyeon-ji's life is a suffocating spiral of debt and despair, a burden left by her father's passing. Salvation comes in the form of a cold, ruthless stranger, Lee Ha-joon, the heir to a business empire. He offers her a simple, transactional deal: pose as his wife for three months to secure his position as the new chairman. The contract is clear—she is his Christmas wife, a temporary solution to a permanent problem, set to leave his life forever after the New Year.

But as the days turn into weeks, their fake relationship begins to feel dangerously real. Trapped in a world of wealth, power, and bitter family rivalries, Hyeon-ji finds herself drawn to the man she was hired to deceive. Ha-joon, in turn, discovers that the woman he saw as a mere pawn is a force he cannot control, a woman whose quiet strength and unwavering loyalty challenge his cold, calculated world.

As the Christmas season ends and the New Year dawns, the contract's expiration looms. But the line between their performance and their reality has blurred. The Christmas wife was supposed to leave, but Ha-joon, now a king on his throne, finds he cannot let go of the one woman who brought light into his life. Their fake love story is over, but their real one is just beginning, a dangerous, breathtaking journey of love, betrayal, and a truth that threatens to unravel them both.