Patterson fills in for Boden, who's trying to clear his name. Severide learns where Serena may be hiding. Herrmann and Otis give Freddie a job that keeps him close by. Jimmy and Chili draw more attention then either bargained for.

Liv, Detective Babineaux and Ravi work together in solving the murder of Chris Allred, who was a high school shop teacher by day, and a vigilante crime-fighter named “The Fog” by night. Liv gets into trouble while on superhero brains and becomes a little too much for Clive to handle. Meanwhile, Major has an eye opening conversation with a new friend. Lastly, Blaine forces Liv to do the unthinkable.

Days before the world's first nuclear explosion, everyone races to secure their place in history.

S.H.I.E.L.D. and Hydra go head-to-head in a battle that will change Coulson's world forever. While Daisy and her team of Inhumans fight to keep Hydra at bay, Coulson and Fitz take the ultimate risk.

When Mark Mardon AKA The Weather Wizard returns to break Leonard Snart AKA Captain Cold and James Jesse AKA The Trickster out of Iron Heights, Barry must stop these rogues from taking over Central City during Christmas. Meanwhile, Joe and Iris meet Wally West.

The evolution of Mindy's relationship with Danny is examined through flashbacks to her start at Shulman & Associates.

Amberle is having grim visions of the future.

The Ellcrys Tree is dying, and the demons are being released.

Democratic presidential candidate Sen. Bernie Sanders (I-Vt.); John Cena (Sisters (2015)). Also: Troye Sivan performs with The Roots.

America's votes are revealed, then three artists sing for America's instant save and the final slot in the Top 4. Dolly Parton mentors and sings, and Season 3 winner Cassadee Pope performs.