智商仅相当于6岁孩子的爸爸龙九和他的宝贝女儿艺胜曾幸福地生活在一起，他有稳定的工作和聪明懂事的女儿，这个女儿不仅每月会自己去交水电费保险费，还会照顾自己和爸爸。龙九即使残障也觉得自己是世界上最幸福的人

某天，执着为女儿买美少女战士书包的龙久意外卷入一起幼童诱拐奸杀案，而死者竟是警察局长的女儿。。当时只有龙九在场，他采取的急救措施，在一群不负责任的警察的教唆指导下，却成了强奸杀人罪的铁证，龙久懵懂无知，搞不清状况，昏头昏脑就被投入监狱。在7号房里的其他犯人们，即使曾经犯过罪，却也有柔软的一面。7号房被他们布置成温暖的样子，他们互相帮助与保安斗智斗勇们冒险将见父心切的艺胜藏在箱子中，千方百计带到监牢内，从此7号房成了温馨的所在。

Long Jiu, whose IQ is only equivalent to that of a 6-year-old child, once lived happily with his precious daughter, Yi Sheng. He had a stable job and A smart and sensible daughter, this daughter not only pays the water, electricity and insurance premiums by herself every month, but also takes care of herself and her father. Long Jiu feels that he is the happiest person in the world even though he is disabled

One day, Long Jiu, who was obsessed with buying Sailor Moon schoolbags for his daughter, was accidentally involved in a child kidnapping, rape and murder case, and the deceased She was the police chief's daughter. . Only Long Jiu was present at the time, and the first aid measures he took, under the instigation and guidance of a group of irresponsible policemen, turned out to be irrefutable evidence of rape and murder. Long Jiu was ignorant, confused and thrown into prison. The other prisoners in Room 7, even if they have committed crimes, have a soft side. Room 7 was decorated by them in a warm look. They helped each other and fought wits with the security guards. They took the risk of hiding Yisheng, who was eager to meet his father, in a box, and tried every means to bring him to the prison. Room 7 has become a warm place ever since.