When he responds to a burglary call, Ray finds two cops murdered in an apparent ambush, and discovers that the shooters were tipped off by someone within the precinct; the FBI locks down the station, leaving Joel to uncover the mole; despite Andrea's nearly costing him his badge a year earlier, Ray enlists her help in tracking down the perps.
Donnie Wahlberg
Detective Joel Stevens
Neal McDonough
Assistant District Attorney David McNorris
Mykelti Williamson
Police Department Detective II Bobby 'Fearless' Smith
Gary Basaraba
Police Department Police Officer III Ray Hechler
Lana Parrilla
Teresa Ortiz, paramedic in season one, rookie police officer in season two
Jason Gedrick
Police Department Police Officer II Tom Turcotte
