Senior Supervisory Intelligence Analyst Kwame Lewis and his team of FBI personnel investigate potential global threats stemming from the Paris terrorist attacks. A nightmare scenario coalesces in the form of a bomb found in Times Square.

Special Agent Barb Daly heads FBI squad C-19, handling violent crimes from bank robberies to would-be cannibals. Across the hall, squad C-20's agents, including Special Agent Danielle Messineo, grapple with investigating child pornographers and other especially heinous criminals.

Special Agent in training Julie Irene balances motherhood with training full-time at Quantico. Special Agent Leo McFarland discusses what it means to be LGBTQ in the FBI today. Special Agents Joe Rudnick and Megan Kirkland introduce a troubled teen to an ISIS cooperator to help him understand the brutal reality of the terrorist organization.

Special Agents Lou DiGregorio and Belle Chen track down members of a new, more insidious mafia. Meanwhile, Special Agents Chris Serrota and Imram Juman collaborate with the NYPD to arrest the gang members responsible for the killing of Officer Randolph Holder.

After receiving intel, the FBI works to stop an attack on the subways; the JTTF meets with a former terrorist, while awaiting verdicts.

Special Agent Frank Pellegrino and his colleagues struggle with lessons learned in their 25-year fight against terrorism.