An AI programmer accidentally develops an AI program called Cho Sang Shin, which will identify trashy humans, and she uses it to save people who are in difficult relationships.

Renowned 70-year-old poet Lee Jeok-yo falls for a 17-year-old girl named Eun-gyo. Upon realizing his love for the teenager, the poet goes through emotional turmoil and self-destruction, while willing to give up his fame as one of the nation’s most respected literary figures. Involved in the love triangle is Lee's student Seo Ji-woo, a novelist in his 30s who also becomes obsessed with the girl.