Lila Mercer has Christmas under control. The Willowmere Winter Market is running on schedule, the cocoa is hot, the decorations are perfect, and her family is expecting her serious boyfriend for a cozy holiday week at the old Mercer house. Then Ryan breaks up with her four days before Christmas. Now Lila has a problem. Her family has already prepared the couple room. Her mother has made up the antique sleigh bed. Her sister is asking about matching pajamas. Her aunt is threatening embroidery. And everyone is ready to welcome a man who is no longer coming. Enter The Stand-In Society. Owen Calloway does not take December cases. Christmas is too loaded, too personal, too full of families turning simple gestures into future promises. But Lila's emergency comes with strict boundaries: no impersonating the ex, no fake forever, no shared bed, no mistletoe pressure, and absolutely no monogrammed stockings without consent. It should be simple. Owen will help Lila arrive with dignity, survive her family's loving chaos, and correct the misunderstanding before Christmas turns one breakup into a full-scale holiday pity festival. But the Mercer family is warm, nosy, and dangerously good at making room. The sleigh bed is not neutral. Stockings are not just socks. Cocoa comes with questions. And the more Owen helps Lila hold the line, the harder it becomes to pretend he is only there because of an assignment. Lila needed a stand-in for Christmas. She did not expect a man who could make her laugh in the middle of disaster, protect her without taking over, and see the truth beneath every holiday performance. Owen agreed to be temporary. He did not expect to find the one place he might want to stay. The Holiday Stand-In is a witty, warm, medium-heat holiday romantic comedy about fake-date boundaries, family chaos, forced proximity, Christmas traditions gone rogue, and the very inconvenient moment when pretending stops feeling pretend.