The third season of this family cop drama finds Jamie (Will Estes) assigned a new partner: brash Vinny Cruz (Sebastian Sozzi), who isn't quite as by-the-book as Jamie is. Before long, his big brother Danny (Donnie Wahlberg) finds himself in a similar situation when his longtime partner Jackie (Jennifer Esposito) decides to quit the force, leaving Danny to team up with several new partners throughout the season. Erin (Bridget Moynahan) is faced with a blast from the past when her ex-husband comes back to town and squares off against her as opposing council in the courtroom. Danny also finds himself crossing paths with his spouse, Linda (Amy Carlson), now that she's returned to her job as a hospital nurse. Also on the domestic front, Frank (Tom Selleck) tries to convince his father (Len Cariou) that it's time to stop driving for safety reasons. By season's end, Frank must also worry about the safety of his officers when a powerful gang declares war on the police department.