Ungyeol, whom Yuyeon saw in her dreams every day, suddenly shows up at her filming site one day. He says he came here with the help of a mountain god, who will forcibly send him back to the past unless he has a physical relationship with Yuyeon in 100 days. While Ungyeol's clock is ticking, Yuyeon is entangled in a chaotic relationship between a perfect actor, Namgung Hwan, and her friend Sera.
