Lee Kang-Doo dreamed of becoming a soccer player, but an accident ended those dreams. His father died in the accident and he broke his leg. Lee Gang-Doo spent 3 years in rehab. Now, he doesn't have anything and just wastes his days. Lee Kang-Doo then meets Ha Moon-Soo.
Ha Moon-Soo makes architecture models. Ha Moon-Soo also endured an accident that killed her younger sibling. She has suffered from guilt that she survived. She has lived her life earnestly, while suppressing her feelings. After meeting Lee Kang-Doo, Ha Moon-Soo begins to express her hidden feelings.
Moon Soo is a pattern maker who starts a work owing to good offer but she is shocked by hearing the hidden stories of big projects. On the other hand, there is peculiar thing happened to Gang Doo who used to live in a back alley every day.
Even though there was an accident, Moon Soo tells Joo Won that she wants to handle the project to the end. Moon Soo feels inconvenient when she comes across Gang Doo constantly. Yoo Jin comes as the project manager and Gang Doo is hired as a site manager.
Moon Soo constantly encounters Gang Doo and she tries to avoid him as much as possible. Joo Won tries to draw a firm line to Yoo Jin. Meanwhile, Moon Soo gets into trouble during the field investigation and someone approaches and offers a helping hand.
Moon Soo heard that the person who broke the monument was Gang Doo. She asks him whether he was at the accident site or not. Gang Doo speaks frankly to Yoo Jin about Joo Won's harsh rejection towards her. Moon Soo goes to Gang Doo after seeing rain.
Gang Doo gives harsh criticism to Joo Won who sees the wrecked construction site. Gang Doo searches for existing tombstones along with Moon Soo for erecting a new monument. Yoo Jin is unhappy with Yoo Taek's poor performance.
Gang Doo feels ominous from the grandmother's changed attitude. Wan Jin looks closely at the eyes of Joo Won in the picture taken by Moon Soo. Meanwhile, Gang Doo is displeased with Moon Soo who always suppresses her emotions and pretends to be fine.
Moon Soo and Gang Doo unexpectedly spend the night together and become closer by bringing up the story of their families. Joo Won reveals his real intention at the family reunion and Yoo Jin feels mysterious as she looks at Joo Won who is devastated.
While Gang Doo and Moon Soo are busy searching for the necessary materials for the construction, Joo Won holds a meeting and makes embarrassing remarks. Yoo Jin makes a big fuss over Yoo Taek's poor handling and she takes care of his business instead.
Moon Soo misunderstands and feels disappointed when she sees Gang Doo and Yoo Jin are together. Gang Doo puts the chill on Moon Soo and starts to toss her to Joo Won. Meanwhile, Moon Soo hears a story from Yoo Jin and recalls the breathtaking truth.
Gang Doo, who went out on a boat, can not shake off the memories of the past and Moon Soo. When the grandmother's health becomes noticeably worse, people try to accept it in a calm manner. Meanwhile, Moon Soo begins to approach Gang Doo more actively.
Gang Doo says last greeting to the grandmother. Moon Soo takes on an unexpected new task and Gang Doo starts to work out for a last request that the grandmother left. Meanwhile, Yoo Jin meets a person who has a hidden solution.
Gang Doo signs the changed contract terms, dresses up and set out for the final job. Moon Soo secretly delivers Gang Doo's medicine to Jae Yeong. Joo Won is shocked by the comments made by Moon Soo who looks at the drawings of the past shopping mall.
So Mi recommends new date places for Moon Soo and Gang Doo. Yoon Ok starts to blame each other by telling Dong Cheol about the past memories. Yoo Jin is deeply shocked by the cold-hearted attitude of Joo Won when faced with the ongoing project.
Moon Soo and Gang Doo express their trauma that they have not talked about for a long time. Moon Soo starts worrying about Gang Doo who comforts her.
Moon Soo can't help but think that she is destined to ruin others' lives. Gang Doo rebukes Moon Soo and persuades her to finish the monument together. Yoo Jin gives Joo Won a strong advice, and Yoon Ok decides to go somewhere.
Upon hearing the news that Gang Doo collapsed, Moon Soo and others volunteer to perform liver transplants to him but there is no suitable candidate. Yoo Jin decides to make a big decision by reviewing the documents she received from Joo Won.