When a raging flood traps a researcher and her young son, a call to a crucial mission puts their escape — and the future of humanity — on the line.

A troublemaking veteran detective and a rich rookie detective go on a work trip to Seoul to reinvestigate a mysterious murder.

As Tae-in moved away suddenly, Do-ha embarked on a long-distance relationship that certainly wasn't planned. Although they talk to each other daily and constantly through KakaoTalk and video chat, they all never enough in fully expressing his love for her. So he secretly plans to propose to her. But for some reason, Tae-in contacts him less and less often. Do-ha feels his trust and confidence in their love breaking down slowly...

Min-ho's adulterous lover Se-hee is murdered in a hotel where only the two of them were present, and Min-ho is immediately singles out as the prime suspect. Insisting on his innocence, Min-ho hires the talented lawyer Shin-ae to defend him, and confesses to her that a car accident on the day before may be connected to Se-hee's murder.