Katelynn Shennett

A mysterious caller who is in danger relies on Kidd to help save her and her brother; the firehouse helps Cruz get ready for fatherhood.

Firehouse 51 deals with the aftermath of the capsized boat rescue; Gallo, Ritter and Violet discuss plans for a side gig.

A video of Casey from the roof rescue goes viral; Mouch sets up a Little Free Library at Firehouse 51; Herrmann breaks protocol.

A mishap on the aerial ladder in the midst of a fire rescue leaves Mouch shaken and questioning his abilities; Kidd looks for support from Severide while Casey and Brett discuss their future.

The firehouse reacts to some exciting news; a mysterious stranger arrives, and a shocking call takes Severide's breath away.

Det. Pryma's case comes to an explosive end with Kidd and Carver's lives in danger. Brett installs an infant Safe Surrender Box at 51. Violet is determined to take Emma down.