As Sullivan rises through the ranks,
Special Investigations Unit chiefs Queenan (Martin Sheen) and Dignam (Mark Wahlberg) recruit rookie Billy Costigan (Leonardo DiCaprio) to get «kicked off» the force and do time to gain Costello's confidence.
The police
chief heading the
investigation is crusader Jack Doyle (Morgan Freeman), who, as the victim of an unendurable loss in his own past, has made it his mission to head a
special victims
unit specializing in missing children — his
chief lieutenants Bressant (Harris, tremendous) and Poole the kind of cops inured to the ugliness and hopelessness of their undertaking.