"Blue Bloods" is a police procedural TV series that centers on the Reagan family, who all work in law enforcement to keep New York City safe. The show focuses on the familial component and how problems within different factions can cause family members to go up against each other. However, two integral members of the Reagan family have never appeared in the series. Betty Reagan, Henry's wife, died of terminal illness before the events of the show, and Mary Reagan, Frank's wife, died from cancer. Despite their absence, their legacies live on through their children, grandchildren, and great-grandchildren.