The team is called to find a missing canister of nerve gas, only to discover a terrorist organisation has aquired it and attached it to the bottom of a plane. Colonel Ryan and Mack attempt to calculate the flight path of the plane, with information relayed from Bob, who is in pursuit in his own aircraft.
Bob volunteers to ram the plane, taking both his and the terrorists aircraft down before the nerve gas reaches St. Louis. He asks to be put through to Kim, but the command center is still only half-repaired after last season's explosion, and the connection can't be made.
Eventually, Bob devises a risky way to bring the enemy plane down in a cornfield, and is successful in doing so without sacrificing his own life.