The adventures of scientist Barry Allen who is a superhero with incredible speed.
Cast: Grant Gustin, Candice Patton, Rick Cosnett, Danielle Panabaker, Carlos Valdes, Tom Cavanagh, Jesse L. Martin, Patrick Sabongui
When the partical accelerator is back online, Barry will have to go back in time to stop Eobard Thawne on the night of his mother's murder 15 years ago.
As Wells once again gets the upper hand on the S.T.A.R. Labs team, Barry realizes he needs to make a big move and reaches out to an old foe, Captain Cold, for help. Joe and Caitlin warn Barry that Cold can’t be trusted. True to form, Cold has his own agenda that involves the meta-humans trapped in the containment cells. As things seem to be going from bad to worse, The Flash gets reinforcements – Arrow and Firestorm.
Barry deals with the latest threat from the Reverse-Flash; Dr. Wells distracts the team by releasing Grodd on the city; Iris and Barry have a serious talk.
Barry, Caitlin, Cisco, and Joe set a trap for Wells. Cisco uses himself as prey which puts him in grave danger. Meanwhile, Eddie makes a decision regarding Iris, which leaves Joe a bit unsettled.
Joe and Cisco visit Starling City and ask Captain Lance for help with their investigation into Dr. Wells; Laurel asks Cisco for a favor; Barry faces a new foe who can disguise himself into anyone he touches.
Felicity Smoak and Ray come to Central City seeking help with Ray's suit; a meta-human releases deadly robotic bees; a group dinner does not go as planned.
A copycat killer who goes by the name “The Trickster” starts setting off bombs in Central City. In order to stop the villain, Barry and Joe meet with the original Trickster, a criminal mastermind named James Jesse, who has been imprisoned for 20 years. Things quickly go from bad to worse when the Tricksters unite and take Henry Allen prisoner. Meanwhile, Iris asks Eddie for help with a case, and flashbacks show how Eobard Thawne came up with the idea for the particle accelerator.
The Flash learns that Captain Cold and Heat Wave have returned to Central City. This time Snart has brought along his baby sister Lisa aka Golden Glider to help wreak havoc on the city.
Mark Mardon, having survived his apparent death during the black-matter explosion, returns seeking revenge on Joe for the death of his brother Clyde and has the same weather-manipulation powers as his deceased sibling.
After the nuclear explosion separates Ronnie and Dr. Stein, Barry and the team believe both men are safe. Barry gets some important information about time travel.
After Ronnie attacks a physicist, Barry and the team go after him. Joe enlists Cisco's help in the reinvestigation of Nora Allen's murder. Barry struggles with his relationship and his duties as The Flash.
Caitlin brings Barry out to a karaoke bar, hoping they both meet someone new; Cisco thinks about Hartley's dangerous proposition; Henry's snooping gets him into trouble.
After his encounter with The Rogues, Barry must face off against a new villain, Pied Piper.
As Barry is struggling to train his speed in order to beat Reverse Flash, his old friend, Captain Cold, returns to Central City with the help of a new villain, Heat Wave.
Barry enjoys holiday traditions with Joe and Iris -- and is faced with his nemesis.
When a new meta-human, Chroma, threatens to take down Starling City, Arrow requires more help than his standard crew, and therefore, the Flash comes to help.
The Flash goes up against Farooq aka Blackout, a metahuman who can harness electricity.
Many people are now aware of the "Red Streak" saving lives, but Barry Allen is eager to make a name for himself. He wants everyone to know who the "Red Streak" really is. Although, his actions cause unexpected consequences.
After a bomb goes off downtown, the army, led by General Eiling, rolls in and takes over the case, much to Joe's surprise. Suspicious, Joe tells Barry that he and his friends at S.T.A.R. Labs should look into the army's involvement.
The Flash stops a robbery but the culprits get away after shooting a guard, and The Flash chooses to save the man instead of following the criminals. Joe shows Barry a book of suspects and Barry identifies Leonard Snart as the leader of the group. Snart revises his plan to steal the Kahndaq Dynasty Diamond and gets a boost when he gets his hands on a stolen "cold gun," which could kill The Flash. Dr. Wells is furious when he finds out that Cisco built the cold gun without telling anyone and now it's missing. Meanwhile, Iris is getting the silent treatment from Joe because of her relationship with Eddie. Finally, The Flash and Captain Cold have an epic confrontation.
As Barry and the team at S.T.A.R. Labs work to capture Kyle Numbus, aka The Mist, a dangerous new meta-human with toxic gas powers, they revisit the painful night the particule accelerator exploded and killed Caitlin's fiance, Ronnie. Meanwhile, Joe decides to finally visit Henry in jail after all these years, but things take a dangerous turn when Kyle shows up looking to punish Joe for arresting him years ago. Meanwhile, Iris and Eddie continue to hide their relationship from Joe.
Iris is escorted by Barry to a university gathering, honouring Simon Stagg, a famous scientist. When six gunmen interrupt proceedings, Barry changes into the Flash only to pass out. While the scientists try to discover what's wrong with Barry, they realize that they're dealing with a metahuman who can replicate himself. Meanwhile, Iris becomes intrigued by the mysterious red streak fighting crime in Central City.
Nine months after the Star Labs explosion, Barry awakens to find a lot has changed while he was in a coma. With his new friends and powers Barry must try to right the wrongs of his new Mentor and Owner of Star Labs.