When the key witness to a company's deadly chemical spill is murdered inside FBI headquarters, King and Maxwell are trapped in the building. With a killer on the loose and Special Agent Rigby's career on the line, they have only hours to solve the murder and find a new witness to testify at a Senate hearing to bring the company to justice.
When FBI Agent Carter is suspended after assaulting an officer, King and Maxwell begin to investigate the circumstances surrounding the incident. What they find leads them on a bizarre trail involving clues from Carter's most recent case. Meanwhile, Sean reveals more about his past as a Secret Service Agent and the mistake that led to his downfall.