When does Blue Bloods return?

Blue Bloods is an American police procedural drama television series that premiered on CBS on September 24, 2010. Its main characters are members of the fictional Reagan family, an American, Irish Catholic family in New York City with a history of work in law enforcement. The show's title references both the "blue-blooded" concept of nobility as it relates to the Reagan family's powerful roles within New York's criminal justice system as well as an entire family who dedicate their lives to law enforcement, one that "bleeds blue"
The series follows the Reagan family, with a long history of policing in New York. Frank Reagan is the New York Police Department Police Commissioner, a post his father also held. Frank's eldest surviving son, Danny, is an NYPD detective and his youngest son, Jamie, is a NYPD sergeant. The show's title references both the "blue-blooded" concept of nobility as it relates to the family's powerful roles within New York's criminal justice system.