"Line Walker" is a Hong Kong action thriller film released in 2016. The story revolves around undercover police officers who infiltrate criminal organizations. The main character, played by Louis Koo, faces challenges as he navigates the dangerous world of crime while trying to maintain his cover. The film explores themes of loyalty, betrayal, and the moral dilemmas faced by those who operate in the shadows. It features a mix of intense action sequences and emotional moments, showcasing the struggles of the characters as they balance their duties as law enforcement with their personal lives.