On Penelope Eckhart's seventeenth birthday, her wish not to be alone gets answered as she summons a bewildered girl from another world - a girl who calls herself Cha Siyeon and claims to know Penelope's future. Aware of the sequence of events and being able to see the game system, Siyeon chooses to help Penelope in hopes of returning back to Korea. But time is ticking, and as the clock counts down to Penelope's coming-of-age ceremony, both of them have less than a year to stop the only ending of the villainess. What neither realizes is that some fates are worse than death.