Ryu Seo-woo is an award-winning best vocalist who tragically died in a plane crash and transmigrated to a BL novel, "Serenade Me, My Angel" which he read out of boredom. He transmigrated into the body of the sub-villain, who shares his name but is a C-list singer with a ruined voice due to throat damage. Living in a decrepit house with his five-year-old triplet sons (Seo-jun, Seo-min, and Seo-jin) who despise him for years of neglect and abuse, Seo-woo is determined to rewrite their lives. The novel's main couple: the stoic CEO Moon Woo-seok and his innocent, angelic singer Jin Yu-jin are destined for a happy ending. In the original story, Seo-woo's character dies in a fire, leaving his genius triplets to be adopted by the main couple. However, the transmigrated Seo-woo has no intention of dying or letting the original plot play out. Can he win over his sons and forge a new path?