Assistant Chief Francis Tierney Sr. is the head of a multigenerational New York City Police Department (NYPD) family, which includes his wife Maureen, their son Francis "Franny" Jr., His wife Abby, Their three children Caitlin, Francis III & Bailey, their son Ray, his wife Tasha and their Megan, her husband Jimmy Egan, their two children Shannon & Matthew. Deputy Inspector Franny is the Commanding Officer of the 31st Precinct, where Sergeant Jimmy is a patrol officer, while Detective Ray works in the Missing Persons Squad, having transferred to this lighter duty after being shot during an arrest two years earlier.