1999. Han Sudjin has just graduated from university. Her future is crystal clear to her: study abroad, a scientific career, and a happy marriage with the love of her life—Kim Hyekkون.
Everything changes with one phone call: “Mom, it’s me, your daughter Jiyeon! I’m calling you from the year 2019 and I need to warn you about what will happen!”
At first, Sudjin is sure it’s just an elaborate prank. But the more she talks by phone with the unknown girl, the stronger her doubts become. Is her future truly predetermined? Or can it be completely overturned by a single wrong action?
Jiyeon warns: after the sixth call, the connection will be cut forever. And during that time, Sudjin will have to make a decision that will change her future… for the better or for the worse.