The city is ravaged with the police unable to handle the metahuman army attacking. The Flash saves a squadron by whisking the metas away, but the rest of the city crumbles under what is known as “Metapocalypse.” Iris reports on the event and reassures the people not to give up hope. Despite the overwhelming odds, Barry believes that he can stop the army. Meanwhile, the team at STAR Labs is surprised to see Caitlin alive and safe. She reveals that Zoom let her go and fears what he can do to Barry. He reassures her that the universe, the Speed Force, is with them, meaning that Zoom cannot win. The rest of the team grows nervous at Barry’s invincible confidence from his trip to the Speed Force.
At Mercury Labs, Dr. Tina McGee works on a project before the building is attacked by a meta with a sonic scream.
At STAR Labs, Cisco keeps an eye on a sleeping Caitlin, worried about what happened to her. Barry still reminds him that the Speed Force is with them. Before Cisco can respond, he experiences a vision where he sees a dead canary. Once he comes back, the news reports an attack on Mercury Labs. Barry races to save Dr. McGee as the building crumbles. When they reach the ground, Dr. McGee reveals that she is aware of the Flash’s identity. In the distance, the meta turns to reveal herself as Laurel Lance’s doppelganger.
Dr. McGee: Come on, Barry. I’m a scientist. We’re paid to be perceptive.
Barry and Dr. McGee return to STAR Labs where she meets up with the others and is introduced to Henry. They ask her if she knows anything about the attack, leading Dr. McGee to remember a security system programmed in the building. It should be able to show them the events prior to the building’s destruction. In questioning why someone would attack Mercury Labs, she also brings up seeing what looked like Dr. Wells just a few months earlier. With what they know, and what they can’t tell Dr. McGee, they go to work.
Meanwhile, Wally patrols the city before spotting a meta trying to steal from a woman. He stands and tries to fight the villain off until he uses his powers. Joe then arrives and uses a STAR Labs device to level the meta while saving his son. He lectures Wally about recklessly endangering himself by trying to help in these situations. Wally reminds Joe that he was saved for a reason, but Joe says that he shouldn’t be throwing his chance away like this. Wally then admits that he needs to prove to the Flash and himself that he was worth saving by helping others.
Back at the lab, Caitlin begins testing Jesse’s blood upon Jesse’s request. Harry questions why she would need to when Jesse reminds him she was hit by dark matter. Within those circumstances, it is just as likely that she would become a metahuman as well. Harry assures her that she is not a metahuman, and, even if she was, she has a genius IQ that could prove to be very helpful during the chaos. Suddenly, Caitlin sees a flash of Zoom. Cisco and Harry both reassure her that Zoom is not there, and he won’t come after her at STAR Labs. Despite her fear, Barry still believes that they can handle the metahuman attack.
Questioning Barry’s confidence, Henry has a private talk with him. He asks about Barry’s experience in the Speed Force which Barry describes as not only a change in his view but a change in himself. Henry responds that he can’t understand where Barry gets the confidence, leading Barry to comment that he can’t understand because he wasn’t always there. Henry apologizes for missing out but assures his son that he’s here now. They ultimately reconcile that disagreement before the team spots a news report featuring the Flash symbol burn upon a building calling him to CCPD. Despite Henry’s warnings, Barry races to the station.
At the police station, Barry comes face to face with Jay who instead talks to Barry about their pasts. He remarks how they had similar backgrounds with a tragic past and the desire to go faster. However, he states that the only difference is that Barry wants to be a hero. With that as a distraction, Jay believes that he will succeed. He proves so by showing Barry the destruction of another Barry, knowing that Barry would want to save the people.
Barry returns to STAR Labs to try and come up with an idea to take out the metas. He theorizes that without the metahuman army, Zoom would be vulnerable. With Cisco, they theorize a form of vibrational technology that could, in theory, stop the army without having to take them down one by one. Unfortunately, they have no idea what it is yet. Once again, Barry assures the team that they can do this. Joe takes Barry aside to talk while Cisco has another vision of various dead birds. Joe reveals to Barry about Wally’s activity. Barry understands Wally’s desire to help though he agrees with Joe that he will try to talk Wally out of dangerous heroics.
In the back of the lab, Cisco and Caitlin become frustrated at the inability to create a vibrational device. Caitlin continues to have flashes of Zoom appear before her, frightening her. Cisco stays by to comfort her, but Caitlin still worries. She states that Jay took away everything from her including her sense of safety and sanity. Cisco reassures her that things will be okay and hugs her.
Wally continues to patrol the streets using a stolen police scanner in his car. Barry as the Flash finally catches up to him to talk. While he is flattered by Wally’s desire to help, Barry insists that the best thing Wally can do is stay safe and leave the fight to him. Wally reminds the Flash that the fight is not only his anymore. Since the city’s in danger, it’s the citizens’ job as well, like Wally. He insists on protecting his new home. Before Barry can persist further, Cisco notifies him on the location of the metahuman behind the Mercury Labs takedown in the city. Barry speeds off while Wally secretly follows after hearing the location.
Wally: No, it’s all of ours. This is my city, too, now, and it’s up for all of us to protect us.
Barry is shocked to find that the metahuman is Laurel Lance’s doppelganger known as the Black Siren. She informs him that the Laurel Lance of this Earth is dead while she only enjoys watching things fall. Unleashing a powerful scream, she knocks Barry down and almost easily beats him into submission. Though she believes she can take him out easily, the Black Siren remarks how Zoom must be afraid of Barry if he must go to this trouble to defeat him. Before she can finish off the Flash, however, Wally rams her with his car and whisks Barry away to safety.
Caitlin and Cisco tend to Barry who, despite some bleeding, is fine. Joe, however, rebukes Barry for not being able to dissuade Wally from running into danger. In Barry’s belief that things are on their side, he still quickly brushes off the accusation. Iris then confronts him on his new-found confidence. While she is glad he feels they can win, she reminds him that fear can be a good thing in reminding him the risks they are taking. Barry finally understands the team’s feelings.
Meanwhile, at the CCPD, Black Siren speaks to Zoom. He recognizes that she failed to kill Barry, but she reminds him that she is the only one of his lieutenants still alive. In the time now, he orders her to keep destroying major buildings in order to keep the attacks random. She asks what his major plan is, but Zoom remains vague.
Fortunately, Cisco and Harry come up with a device known as a universal vibrational disrupter. Since every Earth-2 being vibrates at a different and higher frequency, Cisco figured that they could harness a vibrational force at a high enough frequency to disrupt every being from Earth-2, including Zoom, without harming the citizens of Central City. To guarantee the plan, Harry also develops soundproof headphones to protect himself and Jesse from the machine. However, they quickly learn of Black Siren planning to attack the high rise of the city, where a majority of the city lives. In the desperate situation, Cisco comes up with quick idea.
At the high rise, Black Sire is confronted by Killer Frost and Reverb, Caitlin and Cisco in disguise to distract her. They argue as their doppelgangers that with her powers they could stand up to Zoom himself. Utilizing the same words Reverb said to him, Cisco convinces Black Siren that she could be a god among men. In the meantime, Harry, Henry, Jesse, and Barry begin their plan by starting to activate the machine and having Barry create a sound pressure barrier around the city with his speed.
Black Siren eventually catches on to the two’s charade by tossing a pipe to Cisco. When he catches it with his right hand, Black Siren remarks that all doppelgangers are mirror-images of each other. Reverb was left-handed. Cisco and Caitlin run to escape but stop at a dead end. Black Siren begins a scream, but Cisco stops her with a blast of his own emerging from his hand. She is knocked aside, giving the two a chance to leave. Before Black Siren can follow, the amplifier is activated, effecting every Earth-2 metahuman in the city. The metahumans begin to fall unconscious from the rupture, but the amplifier seems to be affecting Jesse even with her headphones, causing her to suffer intense pain. Desperately, Harry gives Jesse his headphones, causing him to fall unconscious from the attack. Henry assures the others that Harry will be fine. During the attack, however, Zoom manages to escape by creating a breach on his own. Barry begins his cleanup of the city.
The team also manage to lock Black Siren in the pipeline where her powers are useless. Despite her resemblance to Laurel, Barry believes that the should avoid informing their friends in Star City about the incident, stating that she is not the real Laurel. Caitlin remarks that, despite her fear, she felt more at ease helping others than she had before, believing that she will be okay. She, Cisco, and Barry then move for a group hug.
Back at the CCPD, Joe informs Captain Singh about the capture of the metahumans, ensuring him that the ones that aren’t in Iron Heights are being dealt with accordingly. The Flash arrives to corroborate with Joe but states that Zoom seems to have escaped back to Earth-2. Singh then asks to find Barry Allen, leading the Flash to quickly leave for Barry to return. Barry then informs Joe that he will ultimately not talk to Wally anymore since he refuses to stop Wally from being a hero.
That night, Iris throws a celebration party at the West house to honor the end of the metapocalypse as well as Henry’s return home. To Henry’s surprise, Iris also invited Dr. McGee whom he seems to have quickly developed a connection with since their meeting. Iris congratulates Barry on capturing the metahumans, and Barry, feeling more invincible than ever, decides to ask Iris to give their relationship an official try in dating. In the meantime, Jesse congratulates Wally after hearing that he saved the Flash, admitting that she’s proud of him. Joe then gives a short toast to the people around them, leading Cisco to have another vision. Instead of birds, however, he witnesses the destruction of Earth-2 before him. When he comes back, Cisco quickly informs the others, but their party is suddenly interrupted by the arrival of Zoom himself. He takes Henry and dares Barry to follow him. Barry takes off, revealing his identity to Wally.
The two race off until ending at Barry’s childhood house. Zoom proclaims that he will make sure Barry turns out like he did by having Barry witness the death of his parent himself. Henry makes one final proclamation that he is proud of his son before Zoom sticks his hand through his chest, killing him.
- Henry Allen finally meets Dr. Tina McGee. An interesting pair-up considering John Wesley Shipp and Amanda Pays starred in the original The Flash series from the 90's!
- Joe West apparently wants his grandchildren to call him Pop-Pop.
- The show continues to hint at Wally and Jesse's futures as speedsters with Wally's desire to be a hero and Jesse's blood testing.