Joy Sullivan transmigrates into a novel as a vicious side character, bound by a system to ensure the leads' happy ending. She spends a night with villain Luther Voss. He mistakes her for someone else, crashing the leads' engagement banquet to steal the bride. Joy reveals the truth, but Luther abducts her for a marriage license. Joy tries to push the leads together, while Luther becomes a doting husband, leading to a sweet, hilarious romance.
