Aspiring to be admitted to a good university and to become a lawyer, Tasiro Yuusuke, a tenth-grader from Kyushu, enrols in a prestigious high school in Tokyo. Plans are made for him to live in his uncle's house, part of which is rented out while his uncle is abroad on business. A realtor's mistakes leaves Tasiro sharing the house with Kei Yamaba, the most beautiful girl in the school, who is also his classmate. There is the risk that their unexpected 'co-habitation' will be discovered by the school authorities. While he grows increasingly attracted to her, he is often irritated by her innocent and nonchalant attitude towards their predicament. They each develop other romantic attachments, but end up turning to each other.
1930年代,小云、小红(周璇)姐妹被人骗到上海卖给琴师和妓院老鸨夫妇,小云被迫做了暗娼,小红年纪尚小,又天生有一副好嗓子,便随琴师去茶楼终日卖唱。姐妹两人住在贫民窟,在她们对面,住的分别是报贩老王和吹鼓手陈少平(赵丹)。因为闲来无事时陈少平常同小红对窗玩闹,两人渐生感情。小红卖唱时被流氓古成龙缠上,对方欲强霸她为妾,小红找陈少平商量对策,两人本想借助律师将正义伸张,不想律师双眼只认钱,无奈之下只得逃走,而这一过程中,老王对小云由怜生爱,可是小云却因自卑不敢正视。琴师偶知陈少平与小红下落,放风给古成龙,古成龙赶到小红住处时,屋里只有她和小云,两人生命危在旦夕。