While investigating a terroristic threat that goes viral online, Korean authorities discover that a suspect has recently boarded an international flight bound for the United States. When a healthy passenger on the same flight suddenly dies a gruesome death of unknown cause, panic erupts both in-flight and on the ground. With steadily decreasing fuel and international refusals to offer aid, the captain and crew will be forced to take unprecedented emergency measures in an attempt to save the lives of their passengers.

Baek Tae Hwa is the cat’s owner and an airline co-pilot. He has a good background and handsome looks that would make anyone fall for him. Due to his naturally sweet personality, Baek Tae Hwa has often made women cry without meaning to. The pet hotel he uses suddenly closes before his flight one day, so Baek Tae Hwa ends up entrusting his pet with a woman. Go Mi Rim has an ordinary background and is optimistic by nature. She works part-time at a convenience store while looking for a full-time job. Go Mi Rim agrees to take care of the cat owned by her one-sided love interest, but she starts to hear the cat’s voice after being hit by lightning, setting up the plot for an interesting romance to unfold.

Jeong-hoon, who is looking back on his life because of his wife who committed suicide without a will, finds the meaning of happiness that his wife longed for, and visits the sea of memories where he found Geon-hee. A short but intense relationship continues with Geon-hee, who had been struggling with her daughter after divorce with her husband, and she smiles for the first time, and Jeong-hoon feels the small happiness Geon-hee gave him on his bus returning home.

A police detective from 1986 travels in time to the present to save his daughter.