The Smile Has Left Your Eyes (2018)

A TV series centered around the unfolding relationship between free and unpredictable yet dangerous Kim Mu Yeong, who is called a "monster". He is the first assistant in a Korean beer brewery who becomes a suspect when a woman's suicide turns out to be murder. His life begins to change when he meets a kind, warm advertising designer named Yoo Jin Gang, who wishes to be Mu Yeong's safe haven. She bears as many emotional scars as him. Yoo Jin Gang also has a brother, a homicide detective named Yoo Jin Guk, with 27 years of job experience. He strives to "reveal" who Mu Yeong really is and attempts to keep his sister, Jin Gang, away from Mu Yeong, with whom she begins to know. (Source: AJ at MyDramaList)