Dong Hae was raised in America by his beautiful but unmarried and mentally deficient mother who was adopted there. He returns to Korea with his mother because of the woman he loves, but she betrays him. Dong Hae begins to search for his father, creating a new family and finding new romance along the way.

Kim Sun Kyung is a retired police officer and father of three sons, Gun Kang, Hyun Chal and Yi Sang.

His eldest son Gun Kang made many wrong decisions in life, ending up being divorced and going bankrupt. Gun Kang gets remarried to Chung Nan. His second son Hyun Chal is the envy of the town and pride of his father. He runs a number of businesses which are quite successful. His wife Woo Mi often sacrificed her happiness for the benefit of the Kim family. As for the last son Yi Sang, he follows in his father's footsteps by becoming a police officer. Oftentimes the father and the son clash each other. As Yi Sang married Eo Young, the daughter of his father's deadly foe, an ex-convict Sun Kyung traced and eventually arrested a long time ago.

"Three brothers" revolves around their relations full of conflicts and love.

Jung Ha Yoon is a graduate student who successfully passed the bar exam. However, she is not finished as she wants to be a medical malpractice litigation specialist. She works at a hospital to look to gain experience and there she meets other doctors who work there.

Ha-eun’s husband Ju-chang is a mixed martial arts champion who does not hesitate to practice Guillotine chokes or low kicks outside the ring. Ha-eun decides she cannot take it any longer and, in a spur of passion, publicly challenges Ju-chang to a duel in the ring.

Julian has lived off with the money he lures from his rich female customers. But now he faces usurious debts from a hasty expansion of his business, and he will be killed unless he clears the debt in one month. The only way to save himself is to pretend to be the long-lost brother of an heiress and kill her to get her huge fortune. Min, the blind heiress, cold-hearted like Julian, slowly opens herself to him, and he, too, falls for her. But Julian has to pay his creditor and what makes it worse for him is that the illness that took Min’s eyesight relapsed, threatening her life.

Ha-eun’s husband Ju-chang is a mixed martial arts champion who does not hesitate to practice Guillotine chokes or low kicks outside the ring. Ha-eun decides she cannot take it any longer and, in a spur of passion, publicly challenges Ju-chang to a duel in the ring.

Though having never once in her life seen her father, Hyun-soo has never felt his absense, as there is a perfect mother for her. Her mother is also a renowned plastic surgeon, so she is never lonely, surrounded by girls who want beauty consultations from her mother. But her happiness comes to an end as her friends who have received facial surgery from her mother start to commit mysterious suicides by cutting out their faces. She also starts to feel that there is someone else in the house where she lives alone with her mother. One day, she discovers a hidden basement and there, she comes to find a secret from her past, which will bring great turmoil to mother and daughter.