"M Squad" is a television series that aired from 1957 to 1960. The show follows a special police unit in Chicago that tackles organized crime and other serious offenses. It features a mix of action and drama, highlighting the challenges faced by law enforcement officers. The series stars Lee Marvin as Detective Lieutenant Frank Ballinger, who leads the squad in their investigations. Each episode presents a new case, showcasing the teamwork and dedication of the officers. "M Squad" is notable for its gritty portrayal of crime and has influenced many later police dramas.