Officer Carpenter asks to be given her father’s shield number as he was just killed in the line of duty in the Boston PD. The problem is, that was Frank’s late son Joe’s badge number and it’s been retired.  

Frank looks back at the history of that badge and similar ones and finds that all 38 officers who wore it died from either violence or illness. 

The Reagan family takes a vote and decides to grant Officer Carpenter’s request and let her have Joe’s badge number. Shortly thereafter, she responds to a domestic disturbance call and his shot in the chest. Frank worries the number is cursed until he finds out that she was still wearing her old badge. Carpenter asks to know more about Joe Reagan so she can honor him as well by wearing that shield. 

Jamie and Eddie capture Derek Gibbs whom they believe has been robbing and stabbing victim’s on the street but are confused when Sgt. Renzulli lets him go with a bench ticket. When Jamie questions him, Renzulli threatens to write him up. Eddie wants to call IAB or their union rep. Jamie wants to give Renzulli the benefit of the doubt. 

Jamie follows Renzulli as he goes to meet Derek. Renzulli says that Derek was his best friend growing up but got into drugs and he’s afraid he’ll die if he goes back to jail. Derek says he isn’t the person doing the stabbings but he knows who it is so Jamie and Renzulli go to meet him but when he sees Jamie he freaks out, pulls a gun and runs off to catch the perpetrator himself. 

Derek finds guy, named Alfonso, and chases him down with a toy gun but Alfonso stabs him just as Renzulli and Jamie intercede. 

Danny and Baez investigate the case of a mobster, John Vincenti Jr, who was murder in his car with his driver, Ronnie Russo left alive in the trunk. The shooter gave the driver the message that this is only the beginning. Danny and Baez leverage Ronnie to call them when he finds out who John’s brother, Sal, is going to retaliate against for the hit. 

Ronnie never calls and the Vincenti’s start a mob war with a rival Chinese gang, the Black Lotus boys. Then a motorcycle delivery driver comes forward with a helmut cam that has footage of Ronnie shooting John Jr. Danny and Baez set up a sting at Sal’s. When Ronnie shows up to shoot the brother, Danny shoots him first.