With the introduction of Catholicism to Korea in 1784 came social upheaval. People who practiced the new religion were tortured into renouncing it or executed. However, these conditions do not deter Seung-hun and her brother from attempting to spread the religion.

A girl who has failed to be accepted by a first-rate university and is suffering from depression, suddenly finds herself pulled into the past. She meets her parents as teenagers and must somehow find a way to spark their romance before she can return to her own time.