: A major arc throughout the season is Erin Reagan's run for Manhattan District Attorney. This creates tension with Frank, who refuses to publicly endorse her to maintain his professional neutrality, causing a rift at the family dinner table.

: Features the return of guest star Tom Cavanagh as Mickey Patrick, Danny’s childhood friend.

: The season finale brings back several recurring characters and resolves key tensions from the DA race. Frank Reagan Tom Selleck NYPD Police Commissioner Danny Reagan Donnie Wahlberg NYPD Detective Erin Reagan Bridget Moynahan Assistant District Attorney Jamie Reagan Will Estes Field Intelligence Sergeant Henry Reagan Len Cariou Retired Police Commissioner Eddie Janko-Reagan Vanessa Ray NYPD Officer Maria Baez Marisa Ramirez NYPD Detective 13×13 Past History – Thoughts on Jamko