Gyeong-ah works as a caregiver and lives alone. The only one she can rely on is her daughter, Yeon-su, but it's hard to see her after she moved out on her own. Meanwhile, Yeon-su, who is suffering from her ex-boyfriend, Sang-hyun, argues with him again and visits her mother’s house. After Yeon-su left, Gyeong-ah receives a shocking message from a stranger.

放暑假的玉周（崔贞云饰）、东周（朴胜俊饰）姐弟俩随爸爸（梁兴周饰）一起来到了爷爷（金尚东饰）家，再加上久未见面的姑姑（朴贤英饰），一家人在爷爷的二层小楼里度过了充满亲情的夏季时光。《姐弟的夏夜》是导演尹丹菲的长篇电影处女作，没有明星大腕加盟，但却以平凡、温暖的亲情故事一鸣惊人，在第24届釜山电影节中斩获韩国电影导演协会奖、市民评论家奖、亚洲电影振兴机构奖以及KTH奖4个奖项，同时还获得了第49届鹿特丹国际电影节未来之光奖，颇受业界认可。在正式上映前的试映阶段也获得了观众的一致好评。而上映首周预售情况也名列前茅，可谓口碑、票房双丰收。