Mo Gallini

After Air Force One is shot down in the desert, Jack's only hope of keeping the "nuclear football" out of the hands of the terrorists comes from two campers who saw the plane go down.

For the firefighters, rescue squad and paramedics of Chicago Firehouse 51, no occupation is more stressful or dangerous, yet so rewarding and exhilarating.

Severide hides his serious shoulder injury as he tries to rescue a construction worker from a collapsed building; two teens are trapped in a vehicle.

Casey must decide whether to turn in a cop's son who paralyzed a teen in a drunken-driving accident; Severide learns he has a fractured vertebra; Mills is torn between his mother and the job.

When an ER physician is gunned down in the street, Castle and Beckett soon discover that the victim was a mob doctor to a Mafia family run by an old friend of Castle's. Also, against this backdrop of Christmas, Esposito and Lanie reach a defining moment in their relationship.

Chief Boden faces allegations after the death of a homeless man in a warehouse fire.