After an unexpected guest from the future appears at their home, Barry and Iris must figure out how to get her back to the future without disrupting the timeline.
Barry and Team Flash track down a meta that is stealing high-tech weapons, only to cross paths with a new foe named Cicada, who is hunting the very same meta, with nefarious intent.
After Cicada's attack, the team realizes it needs to think outside the box to stop this dangerous new foe; Nora comes up with a plan that ultimately puts a team member in danger; Caitlin delves into her past.
Barry and Iris face the ultimate parenting test when Team Flash battles Spin, a savvy millennial armed with meta tech and a dangerous agenda for Nora; Ralph feels defeated until an unlikely source issues a challenge to help boost his confidence.
Nora lets something slip about the future that devastates Iris; in an attempt to distract his wife, Barry asks Iris to team up to stop a new meta, Rag Doll; Caitlin learns something about her father.
Caitlin, Barry and Cisco learn something new about Caitlin's father; Iris and Sherloque follow a clue about Cicada.
Nora grapples with unresolved anger over her father's disappearance in the future; Barry and the team must stop a powerful new meta, Weather Witch, from killing her own father.
Barry and the team come up with a plan to stop Cicada, but it calls for Barry and Nora to travel back in time to gather some key necessities; Barry hesitates, concerned about his daughter seeing certain parts of his life.
When Barry and Oliver Queen wake up one morning and realize they have swapped bodies, the two set off to find out what disturbed the timeline to cause such a shift.
While Nora grapples with the revelation that Thawne killed her grandmother, Team Flash must stop Weather Witch and Silver Ghost, a new villain who can control engines and motorized technology; Caitlin and Cisco discuss creating a metahuman cure.
During a battle with Cicada, Nora is severely injured; due to Cicada's dampening powers, Nora's speed healing isn't working; Barry and Iris are scared for their daughter's future; an enraged Flash confronts Cicada in a brutal battle.
Sherloque wants to use a memory machine on Barry and Nora to help gain access to Grace's memories; Ralph tricks Cisco into going out for a night out on the town.
Barry and Ralph must go under cover as criminals in an illegal black market to purchase a device that could help them stop Cicada; Iris investigates a lead on Cicada's whereabouts and ends up in a dangerous situation.
After Iris lands in serious danger, Nora races to save her mother; Barry puts the finishing touches on the metahuman cure; Cisco gets a rare night off, and he decides to take Kamilla on a date.
When Gorilla Grodd attacks Central City, Barry and friends find themselves teaming up with King Shark; when they hit a snag, they bring in Dr. Tanya Lamden to try to reach the man behind the shark.
With the meta-human cure ready to use, Barry and the team must figure out a way to subdue Cicada long enough to take it; Killer Frost steps in to help with the plan; Joe eases back into work; Nora isn't happy about her dad's plans to stop Cicada.
Team Flash finds out that suburban mom Vickie Bolen is in danger, and they race to save her; they discover she's a metahuman who is hiding her abilities from her family; Barry encourages Vickie to share her secret with her family.
After discovering that Nora is working with Thawne, Barry and Iris disagree about how to handle their daughter; Team Flash aren't sure they can trust Nora, so they go through her journal to find out how she came to work alongside their nemesis.
When Icicle returns to enact the next phase of his devious plan, Caitlin and her mother must resolve their long-combative relationship to defeat the icy monster; Barry makes a big decision about their family without consulting Iris.
Barry continues to struggle with how he feels about Nora's betrayal; Brie Larvan, Joss Jackam and Peter Merkel return to Central City; Cisco makes a bold decision.
Team Flash is on high alert after Cicada II threatens to unleash a dangerous virus that would put all meta-humans at risk.