Aoki is a failing novelist, and Sol is a failing pop singer. Encountering each other in South Korea, speaking different languages, they and their families somehow end up in a truck heading off into the Korean countryside.
High school student Min-sik moves to a rural village with his family. There he meets Ye-joo, a classmate who became a social outcast after her father was accused of murder.
Yoon-hye likes Da-joo more than just as a friend but denies her feelings for the sake of their friendship. After some events following Da-joo being introduced to a boy, Yoon-hye is not able to hide her emotions anymore.
When his mother goes missing, Lee Ho-yeon sets out to search for her. In the course of that journey, he discovers his parents' pasts during the democracy protests of the 1980s when student activists rose up against the repressive Chun Doo-hwan regime. Reading a book written by his mother, Ho-yeon uncovers a story of hope, love and betrayal, and struggles to understand painful secrets that have been hidden away for thirty years.
Sung-hyun returns after 3-years of studying abroad. All alone in a 14-day self-quarantine, he begins to watch the vlogs of Soo-jin, the woman he was dating before he left. Each wonders if they should reconnect.
"Swallow" depicts the story of Cha Eun-sook, who published a book titled "Jebi," which tells a story of the past during the military regime of Chun Doo-hwan in 1983, and her son, Lee Ho-yeon, who finds himself hidden in the book.