"Above and Beyond" Season 4, Episode 21
An undercover cop in Danny's squad gets killed, and Frank is determined to find the murderer. However, things get complicated when the victim's secret is unearthed. Elsewhere, Nicky turns to Jamie as she looks for an ex-classmate living on the streets.
"Exiles" Season 4, Episode 22
For the season four finale, Danny's investigation into an off-limits case gets him placed on modified duty. He then realizes he's uncovered information that someone wants to keep hidden which he passes on to Frank. Frank becomes concerned with the sheer size of the case and how far it reaches internally.
Tom Selleck as Frank Reagan
Will Estes as Jamie Reagan
Donnie Wahlberg as Danny Reagan
Len Cariou as Henry Reagan
Jennifer Esposito as Jackie Curatola
Nicholas Turturro as Sgt. Anthony Renzulli
Amy Carlson as Linda Reagan
Sami Gayle as Nicky Reagan-Boyle