After nearly twenty years of marriage, Jung Da Jung and Hong Dae Young seem to have settled comfortably into their family life. As the proud parents of a pair of eighteen-year-old twins, the devoted couple have worked hard to build a happy home together. But what appears to be an ideal life from the outside is, in reality, anything but. Fed up with Dae Young’s constant nonsense, Da Jung is at the end of her tether. When Dae Young announces that he has been made redundant, Da Jung completely gives up. Convinced that life would be better without her husband, Da Jung wastes no time in filing for divorce. Shaken by his wife’s decision to leave him and utterly disillusioned with where life has taken him, Dae Young takes stock of his life. It doesn’t take him long to see all the points where things went wrong, and he soon finds himself regretting absolutely everything about his life. The moment these thoughts of regret enter his mind, his body instantly transforms into that of an eighteen-year-old, whilst his thirty-seven-year-old mind remains intact. Suddenly given the chance to start his life all over again, Dae Young changes his name to Ko Woo Young and enrols at his children’s school. Seeing life from a completely different perspective, Dae Young soon discovers that, despite retaining his middle-aged mind, he still has a great deal to learn.