Bok-soo (Kim Hye-sun) supports her husband through medical school by selling fish, but he is ungrateful and looks down on her. She discovers her brother is cheating on her best friend Hwa-shin (Oh Hyun-gyung) and tries to hide it. When she learns her husband Ki-jeok (Oh Dae-gyu) is also having an affair, she sympathizes with her friend. Her mother, who endured an unhappy marriage due to infidelity, joins Bok-soo and Hwa-shin in seeking revenge on their unfaithful husbands.