Eun Ha Won is a high school senior who dreams of becoming a teacher. She faces constant mistreatment from her father, stepmother, and stepsister, while working part-time jobs to save for college.

At the same time, three spoiled cousins—Ji Un, the tough one; Hyeon Min, the playboy; and Seo U, the musician—live together in a mansion called Sky House, often clashing with each other.

When their grandfather insists they attend his fifth wedding, Hyeon Min hires Ha Won as his date to cause trouble. Instead, her confident attitude impresses the grandfather, who offers her a job as a live-in butler. What follows is a mix of comedy, love triangles, and drama in the mansion.