Son Seungwan never done a one night stand (yes, he's that kind of guy), opting for meaningful connection. However, when a stunning woman appears during a flooded in night at the Busan KTX Station, who wanted to distract herself from heartbreak, he makes an exception. Their evening together is intensely passionate, and by morning Seungwan wants to pursue something deeper...

But unfortunately, his mysterious lover has vanished. He resigns himself to the fact that it was only a one-time encounter and he'll likely never see her again. However, three years and seven months later his world is completely changed when she unexpectedly finds him out and drops the three words - you're a daddy.