When an armed robbery ends with the death of a police officer, Frank makes it a mission for the NYPD to bring the suspects to justice. Danny and Maria are able to capture the shooter, but because of the lack of any concrete evidence proving he was the shooter, Erin drops all the charges and forces them to release the suspect. Danny and the rest of the police force are furious at Erin and the District Attorney's office. Frank is unhappy by this turn of events but matters get worse when Frank is forced to provide police protection for our shooter after he complains of being harassed. Tensions rise at the Reagan family dinner when everyone seemingly blames Erin for allowing a cop killer to walk away free. The situation escalates for Erin and the DA's office when fellow cops from the slain officer's precinct stage a "blue flu" by refusing to appear in court on any of the DA's cases. Jamie gets a new partner who, despite Jamie's expectations, is a beautiful, rookie female cop named Eddie. Jamie and Eddie are immediately thrust into the conflict when they are assigned to protect the cop killer suspect.