Eighteen months after parting ways under mysterious circumstances, the FBI team is brought back together by a new crisis.
Jane and Weller return from the midseason break. The team must find a way to work together to track down missing nuclear warheads.
The team must decide whether to trust a prisoner who warns them of a dangerous plot. Roman and Crawford butt heads over how to handle a volatile situation.
As a CIA source threatens to tear the team apart, Rich's place in the FBI is called into question. Roman and Crawford spend some time together.
Remi may be gone, but Jane's life is still threatened by ZIP. Elsewhere, the team tracks down a scientist Roman worked with to find a cure, exposing a deadly cover-up and revealing how she faked her own death, and Zapata comes clean with Reade.
