Story-based off Web Novel "The Amazing Son-in-Law Charlie Wade" 

Kim Taeyeon was the live-in son-in-law of the Hwang family. Despite living with a somewhat wealthy family of some status, he was not treated well. 
He was often ridiculed by his family-in-law and those who encounter him. The only person(s) who had given him any respect was the late Grandpa Hwang and his wife Stephanie Hwang. One day things something changes about Taeyeon and he suddenly has a secret life and he plans to treat those who have looked down on him a lesson.