Roe comes under fire when he kills a murder suspect in public and can't recover the gun he claims the suspect drew on him. Convinced his son was wrongfully killed, the dead suspect's father takes Nina and three others hostage inside the precinct house and demands justice for his son's death. While Al and Mike work with the hostage negotiator, Carrie is tasked with recovering the murder weapon and proving that Roe did not shoot an unarmed suspect.