Junseok is the head of human resources at a car parts plant. His boss tells him to cut down the number of people on the production line, and he must meet with each department head to make difficult choices. At home, his wife is suffering from postpartum depression and he tells her to have a day out, asking her to take care of the rent. She parks the car, with her baby inside, at the curb while making the payment, and loses the car. Meanwhile, Hyeontae, the head of the production line at the same plant where Junseok works, is distressed over having to ask fellow workers to resign. How to Breathe Underwater is about a tragedy that strikes two families on one day. Characters who do not know one another are swept into the tragedy unbeknownst them. In the end, they are met with a tomorrow that is completely different from the irretrievable yesterday. The sequence in which one character’s time and another character’s time are repeatedly shown is reminiscent of director Christopher Nolan’s Dunkirk. (NAM Dong-chul)