Seo Eun-young (actress Shin Eun-gyeong)

A nurse working at a general hospital. She is a caring person who compassionately tends to her patients.
She falls in love with Jung-woo and become pregnant with his baby but he left her without a word.
Then misfortune befalls on her when she is hit by a car.
After recovering from her injuries, she returns to her job as a nurse and cares for Hyung-woo, the son of Shin Jung-ok, chairwoman of a department store.
She subsequently falls in love with Hyung-woo and marries him.
However, it turns out that Hyung-woo and Jung-woo are stepbrothers who had different mothers.
Both Jung-woo and the baby they together return to her one day.

Shin Jung-wook (actress Kim Hae-sook)

As Hyung-woo's mother, she is the chairwoman of a department store.
With her business acumen and cold decision-making skills, she seizes the chairwoman position to run the department store.
She obsesses about the health of her autistic son, Hyung-woo, and is overprotective.

Kang Jung-woo (actor Kim Yoo-shik)

He is a calculating man who will choose money over love.
But he had an unhappy upbringing as he was the illegitimate son of Chairman Kang, founder of a department store.
To succeed in life, he leaves his sweetheart Eun-young and marries Na-gyeong, the daughter of a wealthy family.
But then he learns that Eun-young married his stepbrother.

Kang Hyung-woo (actor Kim Tae-hyun)

He is autistic and totally dependent on his mother for emotional support.
But one day, he meets Eun-young and he gradually opens his mind to the world.

Hong Na-gyeong (actress Lim Ji-eun)

The only daughter of the founder of a construction company.
She has a warm personality and dutifully becomes a full-time housewife.
Although she is a caring and obedient wife at home, she secretly carries on an affair with her ex-boyfriend.