If Hae Jun hadn't been curious, he wouldn't have stumbled upon a time machine. With a few button presses, he quickly figures out how to use it, and that marks the beginning of his journey as a time traveller. Yoon Young is occupied with her job as an editor for a renowned writer, leaving her little time to spend with her mother. Then, suddenly and unexpectedly, tragedy strikes as Yoon Young receives a call that her mother has been found dead.