Erin's trial against a notorious human trafficker is jeopardized when the presiding judge is mysteriously found dead. Danny and Baez are put on the case to investigate foul play. Meanwhile, Mayor Dutton opposes Frank's public safety initiative, but City Council Speaker Regina Thomas devises a plan to help Frank bypass the mayor's veto.
Frank receives an order from the mayor to attend a parade honoring a man who served time for conspiring in an attack against the police. Meanwhile, Danny investigates the return of a teen who suspiciously disappeared 13 years ago; and Jamie and Eddie help a young woman they believe is being exploited by a congressman.
Season 8 begins with Danny considering retirement until Erin asks for his help with a case involving her ex-husband; Jamie and Eddie pose as a couple; Frank clashes with the new mayor.