Lee Dong Hae and Jessica broke up  a week ago because Donghae was caught by Jessica kissing Sun Hye. After the brake up Jessica was really heartbroken. She didn't attend SNSD's Rehersal. She really love Donghae. Taeyeon, Sunny, Tiffany, Yoona, yuri, Seohyun and Hyoyeon notices also how Jessica behaves. So when the girls decided to take revenge on Donghae. The Girls' Plan a very genuis revenge. Yoona will maker Donghae fall inlove with her and broke his heart. What if one day something happen to them that made them commit the biggest mistake ever.