Barry Allen, a forensic crime scene assistant for Central City Police Department, is struck by lightning during a storm that is created after a particle accelerator from S.T.A.R. Labs explodes. In a coma for nine months, Barry awakens in S.T.A.R. Labs, having been placed in the care of its founder Harrison Wells and his assistants Dr. Caitlin Snow and Cisco Ramon. Barry can now move at extraordinary speeds. There were other "metahumans" created from the explosion. One of them, Clyde Mardon, is r
In flashbacks, it is revealed that Joe became Barry's legal guardian but did not let him visit Henry in prison at the latter's request. Barry begins using his abilities to stop minor crimes and help citizens across the city while starting to develop debilitating side effects. While guiding Iris West, who seeks his help to do her school assignment, Barry witnesses a robbery by a crew of men, but passes out while trying to stop them. The S.T.A.R. Labs team determines that Barry becomes hypoglycemi
As the police investigate the murder of one of the city's crime families, Barry suspects that the killer may be a metahuman who can control poison gases. As Barry and Joe work to discover the killer's identity, Wells and his team work to retrofit the particle accelerator into a prison for metahumans where they can begin to find a way of reversing their mutations. This brings up difficult feelings and memories for Snow, whose fiancé, Ronnie Raymond, was killed by the explosion. The team identifie
A group of men attempt to hijack an armored truck carrying a diamond on its way to a museum. Barry stops the crime, later identifying Leonard Snart from a set of police mugshots. Felicity Smoak arrives to check on Barry, after learning that he woke from his coma. Meanwhile, Snart acquires stolen tech to help him continue without any powers. This includes a cryonic gun taken from S.T.A.R. Labs. He begins surveilling the diamond at the museum, but is seen and forced to use his cold gun to escape.
Bette Sans Souci, a metahuman with the ability to turn anything she touches into an explosive, appears in Central City. She is being hunted by General Wade Eiling, and is a former military explosives expert. Barry brings her to S.T.A.R. Labs where the team explains to her that she was changed by the particle accelerator, which bonded bomb shrapnel to her body on a cellular level; and they cannot reverse the process. Secretly, Wells convinces Bette to kill Eiling. Barry races to stop her, and Eil
Barry speeds off to stop a car thief; but the thief's skin turns to steel and Barry breaks his hand while punching. He runs back to the lab before he can be hurt further. The thief is identified as Tony Woodward, Barry's childhood bully. Back at the lab, Cisco determines that if Barry can hit Woodward with a specific velocity at right angle, then he can create enough force to compromise Woodward's metal structure. Woodward kidnaps Iris and demands that she write about him. Barry arrives and mana
Wells returns to his secret room, where it is revealed that he has been documenting Barry's abilities, and using his artificial intelligence, Gideon, to look at events in the future. Barry arrives at a crime scene where the victim was murdered via electrocution, and charred beyond recognition, suggesting a metahuman was involved. While investigating the victim's identity, the team identifies a power drain in the city. When Barry arrives, he is attacked by Farooq Gibran, a man who has the ability
Eddie proposes a task force to hunt down the Flash. A new metahuman, Roy Bivolo, shows up with the ability to send people into an uncontrollable rage, and uses his ability to rob a bank. Oliver Queen informs Barry that he and his team are tracking a killer who uses lethal boomerangs. Barry and Oliver agree to team-up and catch each other's targets. Barry decides to go after Bivolo by himself. Bivolo uses his abilities on Barry; but because of Barry's powers it makes the effects last longer. Oliv
The yellow-suited speedster who killed Nora Allen returns, in search of Mercury Lab's tachyon particle technology. Barry encounters the "Reverse-Flash" and engages him but is swiftly defeated, with the villain insinuating that he and Barry have been lifelong enemies. Ronnie is revealed as the flame-controlling metahuman, suffering from memory-loss after having survived the explosion. Per Henry's advice, Barry confesses his love for Iris before the tachyon particle technology is used as bait to l
As Barry works on improving his speed through various training exercises, Leonard Snart returns to Central City with the cold gun and a new partner, Mick Rory, to set a trap for the Flash. Barry discovers his plan, and agrees with Wells not to engage Snart in the hope that he goes away and no one gets hurt like the last time. Snart and Rory, who now has a gun that can emit absolute hot temperatures, kidnap Caitlin to force Barry out of hiding. Cisco and Barry find a way to defeat Snart and Rory.
While home, Wells receives a threatening call from an unidentified person before using his super speed to save his life from an attempt. Wells informs Barry and the team that the caller was Hartley Rathaway, a former protégé. Rathaway begins attacking his family's business with sonic blasts, and after Barry stops him, Rathaway reveals that he knows a secret of Wells', who states that Rathaway warned him that the particle accelerator could explode, but Wells chose to risk it for the rewards. Cisc
A woman with the ability to teleport to any location she can see breaks into Iron Heights and frees her boyfriend, Clay Parker. The S.T.A.R. Labs team identifies the woman as Shawna Baez. To help Barry, Henry tracks down leads in Iron Heights and finds out that Parker owed money to a local crime boss and is planning a heist to pay it back. Barry learns the location of the heist, finding Baez and Parker and is able to capture her after removing all the lights in a tunnel, effectively making her u
The team attempts to track Stein's whereabouts after he attacks a scientist. They convince Stein into coming back to S.T.A.R. Labs for testing. Wells discovers that Ronnie and Stein's atoms are in conflict, and if it continues they will become nuclear. Stein leaves for a secluded location to safely explode without casualties. Barry and Caitlin arrive and use a device Wells made from the tachyon to separate the bodies, but it apparently does not work, and the duo escapes the explosion, which aler
Barry and Caitlin find Ronnie and Stein alive and separated, which Eiling also finds out. Joe reveals his findings to Barry. Ronnie and Stein realize that their minds are partially connected. Wells visits Eiling, who reveals that he knows Barry's alter ego and demands the F.I.R.E.S.T.O.R.M. project. Wells gives up Stein, who is tortured by Eiling until Barry and Ronnie save him. Ronnie and Stein reunite by the tachyon piece to survive the military onslaught. The duo gains enough control to be ab
Mark Mardon, Clyde's brother, returns to Central City to avenge Clyde's death. Eddie and Linda get jealous of the intimacy between Barry and Iris. Mason shares his knowledge that Wells killed Stagg with Iris and Barry, who tells Caitlin and Cisco, who begins to believe Joe was right about Wells, so he rechecks the containment field that failed to hold the Reverse-Flash. Wells arrives and reveals himself to be Eobard Thawne, a relative of Eddie's and a man from the future who came back in time to
Thawne warns Barry not to change any event for fear that he will create a bigger problem. Barry does not listen and instead captures Mardon and puts him in the particle accelerator. Snart and Rory return to Central City. Snart sends his sister, Lisa after Cisco, whom they force to rebuild the cold and heat guns, and a third gun shooting gold for Lisa, by threatening to kill Cisco's brother. Iris rejects Barry's romantic approach and later Eddie punches him. Barry realizes that Thawne was right a
Barry and Joe go after terrorist Axel Walker, under the alias Trickster. Walker sets a diversion for the Flash and breaks James Jesse, the original Trickster from 20 years prior, out of prison. Jesse and Walker attempt to extort patrons of fundraiser by poisoning them and ransoming the antidote. When the Flash arrives, Jesse and Walker fit him with a bomb that will detonate if he stops moving. Thawne coaches Barry on how to vibrate his molecules so that he can phase through objects, which remove
As Barry works in conjunction with Joe and Eddie to stop crimes across the city, an engineering professor is killed by a swarm of bees at a university. While the team searches for a metahuman that can control bees, Felicity arrives with Ray Palmer, looking for assistance to improve his A.T.O.M. suit. The team tracks another bee attack, but Barry is too late and is attacked by the swarm. The team captures one of the bees, which turns out to be a robot and their suspect just a scientist from Mercu
Barry and Eddie track a metahuman named Hannibal Bates, who can shape-shift into anyone he touches. Bates takes Eddie's shape and frames him for murder. Later, Bates knocks Barry unconscious and assumes his form, but Thawne realizes the truth and prevents Bates from killing Caitlin and Iris. Bates manages to escape. Caitlin develops a serum to suppress Bates' power, allowing Barry to defeat him and clear Eddie's name. Iris reconciles with Eddie, who reveals his cooperation with the Flash. Bates
Barry talks to Gideon and learns about his battle with the Reverse-Flash in the future, as well as key moments in his life that include marrying Iris, a promotion at the CCPD, and the creation of Gideon. With high-tech goggles, the team reawakens Cisco's memories of his alternate-timeline death and the secrets Wells confessed. The team regroups at Joe's house, where Barry reveals his recent time travel and explains his plan to lure Thawne to confess to killing Nora. To trap Thawne, Cisco reverse
While looking for Eddie and Eobard, Barry confronts a would-be thief at the gold reserve, before being disoriented by an unknown psychological attack. Back at S.T.A.R. Labs, Iris confronts Barry about being the Flash. He is able to stop the thief, who turns out to be Eiling, mind-controlled by Grodd. With a lead from Iris, Barry, Joe and Cisco head into the sewers to look for Grodd. The trio realize that Grodd is getting smarter and larger, and during an attack, Joe is kidnapped by Grodd. Cisco
Cisco discovers that Eobard has been supercharging his speed through his wheelchair, which is why he is so much faster than Barry. The particle accelerator is activated by Eobard, who has managed to repair it. The team is able to find and rescue Eddie, who ends his relationship with Iris. Worried that the metahumans imprisoned inside the particle accelerator will be killed when it reaches full power, the team plans to relocate them to Oliver's prison on Lian Yu. In order to set up a safe transpo
Barry visits Thawne in the particle accelerator prison, where Thawne reveals he killed Nora because of hating the Flash, whose future self saved him. Eobard requests Barry to help create a wormhole where Thawne can return to his time, while also allowing Barry to save Nora. Caitlin and Ronnie get married. Eobard tells Cisco that the latter's ability to recall events of alternate timelines was acquired from the particle accelerator explosion. Barry decides to go through with Thawne's offer. The l