因事故而痛失女儿的父亲将这“一天”不断重复，只为能挽救女儿。一天之中有哪些秘密尚待揭开，寻踪觅迹的故事尽在影片《一天》。
金明民饰演世界知名胸部外科专家“金俊明”。只为救助一人生命都会用尽全力却是“零分老爸”。亲眼目击女儿因事故死去的场景后，为能收回覆水，循环往复的“一天”中誓死拼争。卞耀汉饰演救护车司机“李民哲”，申惠善饰“民哲”妻子“美京”，赵恩亨饰演“金俊明”女儿“恩静”。

When a wife becomes the breadwinner of her family after her husband loses his job, adultery becomes part of her life.

During the late 1980s, two detectives in a South Korean province attempt to solve the nation's first series of rape-and-murder cases.

The lives of 4 interconnected South Koreans - a married couple, a novelist the wife is having an affair with, and a second woman the novelist is simultaneously involved with.

With no clue how he came to be imprisoned, drugged and tortured for 15 years, a desperate man seeks revenge on his captors.