“The Flash Is Born” begins with Iris blogging about The Flash on her “The Streak Lives” blog. As soon as she posts it, the Flash “speed reads” it and carries her onto a rooftop. He begs her to stop blogging about him. Iris refuses, but Barry asks her to at least come up with a better name for him besides “The Streak.” Their conversation is cut short though when The Flash hears police sirens nearby.
The sirens are coming from a car chase between a man and a The Central City Police. The police try shooting the man, but his skin turns metallic on contact, deflecting the bullets. When the Flash shows up, the driver eagerly gets out of his car. When The Flash tries punching him, the man’s skin turns metallic again, crushing Flash’s fist. Essentially, Flash just hit an iron wall. The man proceeds to pound away at the Flash, who barely escapes the fight with his life. Flash flees back to STAR Labs, where he finds that he fractured his wrist—even with his advanced healing factor.
Barry wonders how he can fight a “man of steel.” Dr. Wells and the team assure that they will crack the case, but Barry needs to rest. The next morning, Barry reports to the Central Police Department, where he confirms with Captain West that the metal man was indeed a metahuman. Barry must then go see the Central City District Attorney. The DA identifies the metal man as Tony Woodward. Barry recognizes the name. Woodward was a former classmate of Barry and Iris’, who bullied Barry throughout his childhood. After the meeting, Barry and Eddie run into Iris. Eddie asks Barry what’s going on between Iris and him, not knowing that Barry is avoiding Iris.
At STAR Labs, Captain West pays Dr. Wells a visit. He asks Wells if he will help him solve Norah West’s murder case. West theorizes that a man with abilities similar to Barry’s killed his mother. He wonders if it’s possible that someone could have had powers like Barry’s 14 years before acquired them. Wells assures him that it’s not possible.
Elsewhere in the Labs, Cisco tells Barry that he must channel his speed correctly if he is to hurt Woodward, or as Cisco dubs him, “Girder.” Barry trains on the steel test dummy that Cisco constructs for him. When Barry rests, Snow asks him if Barry’s still seeing Iris as “The Flash.” Barry lies and says no.
Later at another of Girder’s crime scenes, Eddie asks Barry about about what’s going on between them. Eddie admits that he actually felt threatened by Barry when he first started dating Iris. Barry has a flashback to his and Iris’ childhood, when Captain West taught the two of them how to fight. In the memory, Captain West tells young Barry to fight smarter, not harder. At the crime scene, Eddie and Barry surmise that Girder’s trail leads to a local brewing company. Eddie and Barry question some workers at the brewery. One of them freaks out and tries fleeing, but Barry and Eddie manage to subdue him. The man reveals that Tony was a former Central City factory worker who disappeared when STAR Labs Particle Accelerator accident occurred.
Elsewhere, Iris works her shift at her Jitters. Then, Girder walks into Jitters and tries flirting with her. Iris deflects his affections. Girder asks why Iris she’s championing the Flash on her blog, and more importantly, if she has any information on The Streak. He destroys Iris’ cell phone, but puts a massive wad of cash in her tip jar. What a nice scumbag. Iris then contacts the Flash through her blog. The Flash meets Iris that night. She tells him that he’s hiding out in Keystone city, and realizes that he’s a metahuman like Barry. Iris wants to help, but the Flash discourages her.
The Flash then speeds to Girder’s Keystone location, an old warehouse. Investigating the scene, he sees cooled mounds of melted metal and empty beer bottles. But, Girder ambushes the Flash and beats him into submission. Cisco and Snow manage to find Flash’s battered body, drag him back to STAR Labs. There, Wells tell Barry that if he hits Girder while moving at Mach 1.1, he could take him down. He must execute the punch correctly though, or he’ll break every bone in his body upon contact.
Later, Eddie and Barry train at Central City PD. Eddie reveals his childhood as a victim of bullying, and tells Barry that his gym teacher taught him to focus his anger and fight with intelligence. He has Barry start punching the punching bag, encouraging him to hit it with all of his might. Across town, Wells and Captain West share a drink. They discuss “the impossible,” and Captain West wonders aloud if the man who killed Norah was powered by a past version of the particle accelerator. He then starts interrogating Dr. Wells, suspicious that he might be involved in Barry’s mother’s murder. Indeed, Wells did move into Central City briefly after Norah West died. Wells is insulted and leaves.
Meanwhile, Iris is abducted by Girder. A Central City cop informs Barry and Eddie of her abduction. Barry then tells Captain West. Girder takes Iris across town to their old high school, where he boasts that he killed the Flash. Iris pulls a fire alarm and tries fleeing, but can’t. The police department picks up the alarm however, and Barry gets their location. He races to the school and confronts Girder. Flash is fighting smarter this time, and avoids Girder’s punches while hitting him with objects other than his fists. But it’s not enough. Girder is landing too many punches on Barry. Barry then remembers that it’s smarter to flee a fight when possible, and runs 5.3 miles away—the perfect distance to accelerate to Mach 1.1. Charging in a direct path, The Flash socks Girder at supersonic speed and takes him down. Not wanting to be the complete damsel in distress, Iris deliver the knock-out punch that subdues Girder. That'll teach him not to crush people's cell phones.
The Flash then takes Girder to the STAR Labs prison. He reveals his identity to Girder, and chastises him for using his human abilities to hurt others instead of harming them. Feeling proud of himself for besting his childhood bully, The Flash unwinds with Cisco and Snow. Upstairs, Captain West apologizes to Dr. Wells for suspecting that his Particle Accelerator work is somehow involved in Norah’s murder. He discovered that Dr. Wells lost his wife right around the same time Norah Allen did. With their trust and respect for another restored, the two agree to continue their hunt for Norah’s murderer.
But the two aren’t the only ones to make amends. Barry approaches Iris and apologizes for distancing himself from her. The two put the past behind them. Unfortunately, Iris discusses how she’s following tons of metahumans now, including one who sounds a lot like Pyro. Then, Barry suggests that Iris rename “The Streak’ as “The Flash.” It catches on.
The episode ends with Captain West looking into old case files on Norah’s murder. But his work is cut short when is is paid a visit by “The Man in The Yellow Suit”—or Professor Zoom. Zoom creates a small vortex in West’s house before leaving him unharmed. But he leaves message written on West’s wall. It says, “Stop or else.” Below the message hangs a photo or Iris, tacked to the wall with a dagger.