Mo Gallini

Following the gutsy firefighters, rescue squads and paramedics of Firehouse 51. No field is more dangerous yet so exhilarating, but the personal lives of these men and women provide close competition.

Darden's widow publicly blames Severide for her husband's death and Casey makes a decision about his future with Hallie.

Casey falls under the thumb of a rogue cop after a horrific car crash, while new girl on the block Nicki pays Severide special attention.

Pete rethinks his career after learning that not every call has a happy ending, and Shay decides if she has a future with a married woman.

Chief Boden comes under fire when the press blame him for the death of a homeless man, while Shay has a nasty run-in with her ex-girlfriend.

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.