Betrayed by her best friend, Krystal is sold to the Yang family, as one of the family's household maids. There, she meets Yang Yoseob, the only son and the only heir to the Yang family business. Krystal doesn't take notice of Yoseob at first,  but slowly falls for him unknowingly. Yoseob, on the other hand, falls head over heels for Krystal at first sight. The Yang elders deeply love her and decides to not make her a household maid due to her intelligent and beauty, and decides to appoint her as Yoseob's personal assistant in order to help their heir. What will happen when Yoseob confesses to Krystal, and what will happen if other BEAST members join in making it a love heptagon (love with 7 sides)?????