Blue Bloods

 The series follows the Reagans, a family who has a history of work in law enforcement. Frank Reagan is the New York Police Department Police Commissioner. Frank's eldest son, Danny, is an NYPD Detective, his youngest son, Jamie, is an NYPD Sergeant, and his daughter, Erin, works as an Assistant District Attorney. Frank's second son, Joe (though the series mistakenly refers to him as the eldest in more recent episodes), was murdered by a corrupt cop in the line of duty in events that predate the series, when he was involved with an FBI investigation of a group of corrupt NYPD cops known as the Blue Templar.