Law and Order 21x10 "Black And Blue" Season 21 Episode 10 Promo (Season Finale) - The murder of an off-duty NYPD detective threatens to tear the city apart. Cosgrove mourns the loss of a friend and asks Capt. Benson for help solving the case. McCoy and Price disagree on how to prosecute the culprit, sparking sharp condemnation from all sides.