Cha Jinwook, a rich playboy set to inherit his dad's company, has a chance encounter with Lee Yumi, who has more modest ambitions to become a nutritionist.

After sharing a night with Jinwook, Yumi departs, never to see him again. Three years later, she achieves her goal of becoming a nutritionist.

Yumi struggles to meet the unreasonable demands of her boss. When she goes to apologize to him for a harsh e-mail, she runs into someone unexpected.

When Yumi brings a meal to Jinwook's office, she encounters him with Joo Hyeri. Hyeri is jealous that Yumi is cooking for Jinwook.

On her day off, Yumi takes her half-brother, Donggoo, to Jinwook's house to cook a meal. Once there, Donggoo accidentally breaks an expensive jewelry box.

Jealous of Yumi and Jeong Hyeontae's growing friendship, Jinwook makes Yumi work overtime to prevent the two from spending more time together.

Yumi agrees to pay for the jewelry box and medical fees by having dinner with Jinwook 10 times. They schedule dates for after work and on days off.

During a business trip, Yumi and Jinwook stay at one of the company's resorts. Meanwhile in Seoul, the jealous Hyeri pays a visit to Hyeontae.

When Daebok sees Jinwook playing with Donggoo, he thinks that Yumi and Jinwook had a child. Jinwook also begins to wonder whether Donggoo is his boy.

Hyeri harasses Yumi for stealing Jinwook from her. Meanwhile, Daebok visits Yumi's home to find out if Donggoo is his grandchild.

After deciding to quit her job, Yumi leaves Seoul and moves to Daejeon to work at a university dining hall. One day, Hyeontae comes to visit her.

Yumi blames her mom for her misfortune and goes to the beach where she first met Jinwook. He learns of Yumi's whereabouts and they reunite.