Oliver makes a bold move against HIVE when the city is attacked. Meanwhile, Malcolm checks in on Thea and leaves her with a warning; and things take a horrible turn when Damien Darhk retaliates in a brutal manner at Oliver’s mayoral holiday party.
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.
A new threat emerges.
Gloria wins a silent auction to have a therapist come for an afternoon with the adults; Haley and Alex consider dumping their boyfriends.
Oliver and Barry Allen take Kendra Saunders and Carter Hall to a remote location to keep them hidden from Vandal Savage while they figure out how to defeat him. Malcolm arranges a meeting between Vandal, Green Arrow and The Flash that doesn’t go as planned. Meanwhile, Felicity, Thea, Diggle and Laurel work with Team Flash to come up with a weapon powerful enough to destroy Vandal Savage.
Ward’s campaign for revenge brings the S.H.I.E.L.D. team to their knees, and Coulson proves he will do anything to settle the score.
Vandal Savage arrives in Central City and sets his sights on Kendra Saunders. After Vandal attacks Kendra and Cisco, they turn to Barry for help. Realizing how dangerous Vandal is, Barry takes Kendra to Star City and asks Oliver and team to hide her until he can figure out how to stop Vandal. However, things quickly go from bad to worse when a man with wings AKA Hawkman shows up and flies off with Kendra. Meanwhile, Harrison develops a serum to make Barry run faster and asks Jay to test it out.
This cross-over episode concludes on Arrow’s season 4 “Legends of Yesterday” episode.
The CIA and BND make a play.
Alicia and Lucca join forces with Louis Canning to defend a website accused of racial profiling. Meanwhile, Eli and Ruth worry about the nature of Alicia’s relationship with Jason and how it could impact Peter’s presidential campaign.