A major family secret is unearthed for the Reagans as Sean does some detective work in the gripping season finale.
Frank battles with City Council Speaker Regina Thomas over protests against police brutality; Jamie and his nephew, Joe Hill, try to locate a missing Danny and Baez; Eddie helps an abrasive woman find her father's body.
Eddie and Jamie deal with a domestic violence case associated with an investigation led by Danny and Baez; Frank and his friend go on a mission to avail themselves to an unfiltered look at the city; Erin is presented with a surprising offer.
Frank struggles after Joe Hill's lineage as a Reagan is revealed; Erin and Anthony receive gift-wrapped evidence; Danny's opposition to authority clashes with Jamie's adherence to the rules, as both brothers work to solve a murder.
Danny and Jamie clash over a gang-related shooting; Erin and Anthony search for answers when a lawyer in their office jeopardises a case involving Erin's nephew; Frank grows concerned when he's not invited to speak at a policing forum.