While Jane and Weller partner with a mysterious man from Jane's past to find a missing person, the team races to stop an arms deal.
While Jane struggles to cope with a secret from her past, the team races to prevent an international crisis.
The team must decide whether to trust a prisoner who warns them of a dangerous plot. Zapata is caught between the FBI and the CIA. Roman and Crawford (special guest star DAVID MORSE) butt heads over how to handle a volatile situation.
Weller and his former FBI partner reunite for a dangerous undercover mission while Zapata interrogates a past foe.
After some personal strife, the team must find a way to work together to track down missing nuclear warheads.