The Girl Next Door 2 is a gripping movie about the main character Sejin losing interest in his wife Ahae and Ahae's husband Treat her with indifference. However, after Sejin is poisoned at work and becomes depressed, he receives a message at the alumni association that changes his decision to attend the meeting. At the meeting, he meets the girl-next-door Ara, who has a crush on his childhood and is still happy with his appearance. Lonely Ahae is hurt by her husband's indifference, while Sejin has an affair with Ara's beautiful young brother
In the story, the marriage between Ahae and Sejin is in crisis and Sejin is in trouble because of depression . When they meet their neighbor Ara, they form a strange connection with each other. Loneliness and loneliness made them attract each other, and fell into a short-lived passion overnight. However, as time goes by, Ahae is gradually abandoned, and Sejin starts to recall all kinds of good times with Ahae. They can't help but wonder if they will ever be able to go back to their normal lives and escape this taboo past.