At the beginning of the season Sylvia becomes pregnant with Andy's child. A baby boy, Theo, is born towards the end of the season. This is contrasted with the fate that awaits Sipowicz's older son, Andy Jr., who announces that he is to join the police force. Andy is finally bonding with his estranged son when he is gunned down, which leads the elder Sipowicz to fall off the wagon. Andy Jr's murderers are killed themselves by Simone in an act of self defense.
Bobby and Diane, whose relationship had been put on hold while she attended AA, resume their relationship only for Diane to begin drinking again when her abusive father beats her mother. Her father is eventually killed and her mother becomes the prime suspect.
James Martinez and new detective Adrienne Lesniak begin an affair but only after Lesniak tells Medavoy that she is gay, then that she is not; Martinez later breaks up with her due to her controlling and unpleasant behavior, and Lesniak eventually leaves the squad. Medavoy himself leaves his wife, recognizing that she is holding him back but it is too late to save his relationship with Donna who leaves to take up a job with Apple.
