Film director Jin Young walks out the door after presenting a screenplay that he hopes will be turned into a film. On his way to the parking lot, he meets an attractive woman named In Ae and spends the night with her. Next day, he receives a phone call from Sang Ho, a producer whom he has not heard from for the last three years. Jin Young meets the producer, who's now confined to a wheelchair after a hit-and-run incident. Distraught by his wife's infidelity, Sang Ho asks Jin Young to shadow her, cathing her affairs on camera. Shockingly, the wife turns out to be In Ae, and Jin Young now faces a dilemma...
Ho-sang's car is overturned on a journey with his wife, Min-jeong. She falls into a coma because of this accident and Ho-sang is distressed by her condition. One day, he finds a man's signature on his wife's book titled [Sundays in August] and gets jealous. He finds out that the man and his wife were planning to visit a mountain villa, and he decides to visit the villa by himself. Meanwhile Si-nae, Min-jeong's doctor, is interested in Ho-sang and the book [Sundays in August]. Si-nae calls So-kook in a secondhand bookstore to order the out of print [Sundays in August]. This book reminds So-kook of his dead friend.
