Kang Baek Ho has been friends with Ham Yi Seul for the past twenty years, but has never mustered enough courage to tell her his true feelings. Now, on Valentine's Day, it might be too late. He races to Yi Seul's wedding as her "man of honor" and sadly watches her marry another man, Kwon Jin Won. Full of regret, Baek Ho wishes desperately that he could have done things differently. Enter the Conductor—the man who can help fulfill Baek Ho's deepest desires. Able to control time, The Conductor sends Baek Ho back to high school for another chance at taking control of his own destiny. A sweet, youthful melodrama, Operation Proposal asks the question: If you had the chance to re-live the past, what would you change? Yoo Seung Ho (God of Study) and Park Eun Bin (Queen Seon Duk) reunite onscreen as the fated couple, with Lee Hyun Jin (Heartstrings) and Kim Ye Won (Flower Boy Ramen Shop) rounding out the youthful cast of this fantasy melodrama.