Battle for Happiness

While selecting the winners for a social media event, Jang Mi-ho gets in touch with Yu-jin, a bad relationship from her past. Meanwhile, Yu-jin is cornered by other moms who suspect her of lying for the main role in a play. One day, Mi-ho shows up in front of Yu-jin and fearing that her past will be discovered, Yu-jin gives money to Mi-ho to silence her.

Because of an incident during the play, the event is suspended, and Yu-jin and Ji-ye argue over whose fault it is. Yu-jin accepts Mi-ho's offer to shoot a commercial, but the shoot is canceled when Ha-yul gets hurt on set. The emotional rift between the two deepens. Mi-ho goes to Yu-jin's house to apologize, but is kicked out. The next day, Mi-ho hears shocking news about Yu-jin...

Rumors spread at work that Mi-ho is directly involved in Yu-jin's death. Meanwhile, Mi-ho goes to the aquarium with Ji-yul and Ha-yul. While returning to work with a complicated mind, she gets a call that the girls have disappeared. It turns out that they got lost while going to see Mi-ho. Mi-ho decides to take time off work to care for Ji-yul and Ha-yul, and moves into ‘High Prestige.’

Mi-ho is clumsy in everything about childrearing, and she doesn't fit in properly with other moms. Na-young shows hostility towards Mi-ho and Mi-ho learns from Ji-ye that Yu-jin had a grudge against Na-young in her lifetime. After Mi-ho witnesses Na-young's serious delusional jealousy that doubts her husband's conduct, she finds a picture of Tae-ho's affair in Yu-jin's house.

Mi-ho takes the pictures of Tae-ho’s affair to the police but fails to see the detective in charge. After an argument with Mi-ho, Na-young goes to Jung-ah to kick Mi-ho out, but Jung-ah doesn’t comply. When Mi-ho learns Tae-ho is having an affair with A-ra, she decides to apologize to Na-young. Meanwhile, after being humiliated by the other moms over lunch, Na-young decides to hang herself.

Mi-ho finds Na-young just in time and saves her life. When words get out about Na-young’s suicide attempt, Jung-ah blames it on Mi-ho and looks into her past. Meanwhile, Mi-ho gives up on finding Yu-jin’s killer and returns to work. But feeling guilty, she decides to look after the kids and find the truth about Yu-jin’s death. One day, she receives an anonymous text about the USB.