Simone utilizes her informant to track down an arms dealer on the FBI's Most Wanted list; Brendon investigates a risky lead on a congressman; Cutty and Simone struggle to see eye-to-eye.

When the team splits up to question a suspect's father, Simone and Laura discover critical information on how their abusive relationship is connected to the crimes. Following this lead, the team heads to Tucson to save the suspect's newest target. Meanwhile, sparks fly with Laura and her former colleague, Mark Atlas, as they debate the killer's motive.