Danny and Maria investigate the murder of a man who was shot in cold blood in front of his teenage son. Danny is determined to find justice for this boy and follows up on a clue that leads him to a suspect, Raul Delgado, but Frank calls him to tell him that Immigration and Customs Enforcement (ICE) has told him to back off of Delgado because he is a prime informant in a drug case. Danny is furious that ICE is protecting and hiding a murderer, but with some advice from Erin, Danny finds a way to go around ICE and arrests Delgado. Delgado goes on trial with Jack Boyle representing him, but when things start to look bad for his case, Delgado pulls a security guard's gun and holds everyone hostage. Jack tries to calm the situation down, but when Erin tries to help a panicked clerk, she gets shot in the shoulder. Danny and Frank are called to the scene with Danny taking the lead in the hostage negotiations. Meanwhile, Jamie and Eddie respond to a terrible traffic accident involving a mother and her young son. Traumatized by the accident, the boy clings to Jamie and asks him to come to the hospital with him. Jamie's lieutenant, however, orders Jamie to stay at the scene, but Jamie disobeys the order and gets suspended. The matter is brought up to Frank who must decide what kind of punishment needs to be levied against Jamie.