Danny and Jackie are assigned to protect a key witness in a Russian mob trial, but when an attempt is made on her life, they realize there is a leak on the task force. Meanwhile, Erin is offered a job as deputy mayor, which would have her working directly with her father.
Elenco: Tom Selleck , Donnie Wahlberg , Bridget Moynahan , Will Estes , Len Cariou , Sami Gayle , Marisa Ramirez , Abigail Hawk , Vanessa Ray , Gregory Jbara , Robert Clohessy , Andrew Terraciano , Amy Carlson , Jennifer Esposito , Steve Schirripa .