When broke artisan Ji-hye needs a grant to save her family's Christmas ornament shop, she tells a tiny lie on the application-she's engaged to a fake, high-powered CEO. But when the real CEO, the impossibly handsome and ruthless Lee Han-joon, confronts her, he sees an opportunity. He'll play her fake fianc for the grant, but in exchange, she has to be his for the holidays, attending corporate events and family gatherings as his girlfriend. It's a deal with a strict "Santa's Contract Clause."
As their fake relationship navigates a high-stakes world of rivalries, manipulative exes, and a family that's a little too eager for them to be real, Ji-hye and Han-joon find that the line between their contract and their hearts begins to blur. With Christmas fast approaching and the contract about to expire, they must decide if the greatest Christmas gift is a lie that saves her shop or a truth that changes his life forever.