25年前,高中生任娜美(沈恩京 饰)一家从全罗道搬到汉城,娜美入读真德女子高中,因方言浓重怯于开口的娜美幸运的得到了同班大姐头夏春花(姜索拉 饰)的维护,并与围绕在夏春花周围的执着于双眼皮的金玫瑰、满嘴脏话的黄珍熙、梦想成为作家的徐金玉、要成为韩国小姐的俞福姬以及沉默傲慢的美人郑秀智等五人结识。在一次和不良少女团对决之后,春花和娜美等七人组成了“Sunny”团体……多年以后,家庭主妇娜美在去医院探望母亲时偶然重逢了身患绝症住院的春花,后者希望在生命的最后两个月内,能够再见当年的Sunny成员。娜美找到金玫瑰,两人委托私家侦探寻找当年的同伴,而那些关于青春的回忆,也在一个个熟悉的名姓后面再次被唤醒。
Based on the novel by Karel Capek, the prominent Czech writer of the early 20th century who coined the word robot for his play R.U.R., the story revolves around a discovery of Krakatit - a powerful explosive - by Prokop, an experimental scientist who, following an accidental explosion in his lab, slips in and out of delirium. When he realises that, in a delirious period, he has given the formula for making Krakatit to one of his colleagues, he tries to find the man, who does not realize how dangerous a thing Krakatit is. In the process, he nearly gives his discovery away again to foreign interests, a group of anarchists, and even greater forces of darkness...