The Pregnancy Pact

Kim Lisa (Ji-soo) tries so hard to please her abusive father that she got engaged to someone she doesn't have any romantic feelings for. When the engagement ends, she is devastated and goes to a bar, only to lose her virginity to a stranger whose name she can't even recall. She later discovers she's pregnant and her father threatens to throw her out on the street if she doesn't find the father of the child.
Choi Do-yun, the stranger, is married to another and cannot be able to bring Lisa into his home, and instead, asks his best friend to take responsibility for the child in return for a favour.
Na Su-ho has been living a quiet life for most of his life. Everything is about to turn upside down, though, when his best friend begs him to take care of his mistress who is carrying his illegitimate child.
Kim Eun-hyeok has been hiding his feelings for his sister for as long as he's known. What happens when she goes ahead to live with another man?
Few weeks later, a Lisa notices a stalker. Is her life in danger, or is a secret about to be revealed?
Keep reading to find out how everything plays out.