Chan-woo, who has been studying to become a police officer for 5 years, joins his friends for dinner to ask for the money to apply for his exam and ends up getting drunk. He completely blacks out and wakes up not remembering what happened in his next door neighbor's room. Not only that, he finds a bloody corpse in the middle of the room. He hurries back to his room and tries to report the incident but he had forgotten his phone in the other room. But the door is locked and he has to resort to using a rope to swing to the next door room outside the window. Once the phone is recovered, he cannot go back because of a group of cultists who are evangelizing the neighbors in the hallway. He knows it’s the last day to apply for his exam and gets antsy as time is running out.

朴河宣自2017年的影片《青年警察》后，时隔两年再次回归大荧屏。《第一个孩子》讲述的是生完孩子后，结束了一年的育儿假期而复职的“静雅”的故事。朴河宣饰演的“静雅”是一个三十多岁的普通韩国女性——服装公司代理兼职员“朴宇石”（吴东旻 饰演）的妻子，同时是一个刚出生14个月孩子的妈妈。复职后的“静雅”在残酷的现实中“混乱不已”——虽然想同时兼顾工作和照顾孩子，但却被看似理所当然实则是强加在女性身上的育儿负担压得喘不过气来。

该片讲述了怀着各自不同的故事，每天都在临终关怀病房等待死亡的人们在少女“秀美”出现后发生的故事。

对分手的女朋友恋恋不舍的“在勋”（金来沅）。像平时一样以宿醉开始的清晨，发现自己和不认识的电话号码的某个人有通宵2小时的通话记录他得知电话那头正是！和自己互通姓名还不到24小时的职场同事“善英”。和男朋友处在有心结的分手中的“善英”（孔晓振）。到新公司上班的第一天，那个该说的不该说的全都说出口的和男朋友分手的现场偏偏！被同一个职场的“在勋”看到了。见面才一天时间，比起工作上的事情，反而对彼此的恋爱史更为了解的两人。但微妙的紧张感和尴尬都是暂时的即使是“不像话”“无语”的碰撞也还是牵挂为什么呢？

Chan-woo, who has been studying to become a police officer for 5 years, joins his friends for dinner to ask for the money to apply for his exam and ends up getting drunk. He completely blacks out and wakes up not remembering what happened in his next door neighbor's room. Not only that, he finds a bloody corpse in the middle of the room. He hurries back to his room and tries to report the incident but he had forgotten his phone in the other room. But the door is locked and he has to resort to using a rope to swing to the next door room outside the window. Once the phone is recovered, he cannot go back because of a group of cultists who are evangelizing the neighbors in the hallway. He knows it’s the last day to apply for his exam and gets antsy as time is running out.

两位在学生时期曾是死对头的优秀医生在因缘际会之下重逢，两人双双陷入人生中最糟的低谷，并意外地在对方身上寻得慰藉。