The Major Crimes squad investigates the mysterious disappearance of a teenage girl, who vanished while volunteering at a homeless shelter, while Buzz cracks open the decades old cold case file on the murder of his father and uncle. Andy Flynn considers selling his house.

After an ISIS-inspired attack against a member of the US Armed Services, the FBI asks for Captain Raydor's help in finding a terrorist, as Major Crimes joins the Bureau in a race against the clock before the terrorist can strike again.