After an encounter with a particle accelerator Barry Allen awakes from a nine-month coma to discover that he has become the fastest man alive, and takes on a dangerous bank robber who has the ability to control the weather.
Barry tries to stop a team of six gunmen who are targeting one of Central City's most brilliant scientists, only to discover that his opponent is just one man -- a metahuman with the ability to replicate copies of himself.
After the murder of a mafia family Barry and the team tracks a metahuman who can turn himself into toxic gas. Meanwhile, the need to create a prison that can hold metahumans forces Barry's friends at S.T.A.R. Labs to revisit the night the particle accelerator exploded and killed Caitlin's fiancé.
After he stops a robbery Barry is targeted by the ringleader, who has come into possession of a prototype cold gun developed by Cisco -- capable of freezing the Flash in his tracks. Meanwhile, Barry's friend Felicity pays a visit from Starling City.
The Army's General Wade Eiling swoops in to take control of the investigation after a bombing at a downtown points to a powerful meta-human. Meanwhile Joe and Barry try to discourage Iris when she begins pursuing "the Streak" for her blog.
Barry squares off against an old school bully who has become a meta-human who can turn himself into steel at will. Eddie starts asking questions after seeing the man's supernatural powers in action, and Joe asks Dr. Wells for help solving the murder of Nora Allen.
An encounter with a metahuman with the power to siphon electricity leaves Barry drained of his speed, and Star Labs itself under siege. Meanwhile, William Tockman orchestrates a hostage crisis inside the Central City Police Department, with Joe and Iris among his captives.
When Oliver, Felicity, and Diggle come to Central City to investigate a case, Barry calls upon them for help in tracking a metahuman who can incite people to murderous rage with only a look. But when Barry is affected, those closest to him become the targets of his buried anger.
Barry comes face-to-face with another speedster, the man who killed his mother -- but both he and the S.T.A.R. Labs team find it difficult to keep up with him. Meanwhile Iris receives a Christmas surprise from Eddie, and a fiery new metahuman reveals himself to Caitlin.
Leonard Snart returns to Central City with a new partner, "Heat Wave," intending to set a trap for the Flash. But Barry chooses to focus instead on getting faster so he can keep up with the "Reverse Flash."
The S.T.A.R. Labs team find themselves under attack when Dr. Wells' brilliant former protégée returns with a vendetta -- and high-powered sonic weaponry. Meanwhile, Iris begins a new job as a cub reporter for the local newspaper.
A young woman with the power to teleport breaks her boyfriend out of Iron Heights, and Henry Allen finds himself in the infirmary after asking questions to try and help Joe and Barry. Meanwhile, Cisco attempts to learn what Hartley knows about Ronnie, and Caitlin and Barry spend a night on the town.
After a scientist turns up in critical condition Barry and the team must try to find Caitlin's fiancé Ronnie, a dangerous meta-human now under the control of Dr. Martin Stein. Joe enlists Cisco's help in running forensics on the room where Nora Allen died, and Barry struggles to maintain his heroics and his relationship with Linda.
While Dr. Stein and Ronnie Raymond attempt to resume their individual lives, General Eiling targets them in a desire to control Firestorm. Meanwhile, Barry learns that time travel is possible and may be in his own future.
The brother of the Flash's first meta-human opponent targets Joe with weather powers in order to avenge his brother's death. The team begins to suspect that Dr. Wells may not be what they think, and Cisco attempts to reconstruct how the Reverse Flash escaped his containment chamber.
Captain Cold and Heat Wave return to Central City with Snart's sister, blackmailing Cisco into making them new weapons. Meanwhile Barry reveals to Dr. Wells that he has traveled in time, but cannot convince Iris that she has feelings for him.
Attacks by a copycat killer called "the Trickster" send Joe and Barry to James Jesse, the original Trickster who has been incarcerated for 20 years. In the past, Harrison Wells comes face-to-face with a man who will change his life.
A disgruntled scientist unleashes a swarm of high-powered bees in order to exact revenge on her former co-workers. Felicity brings her new boyfriend Ray to town for help with his new Atom suit, and a frustrated Iris gives Eddie an ultimatum.
Barry chases a meta-human who can impersonate anyone simply by touching them, who lands Eddie in police custody for shooting two police officers. Meanwhile Joe and Cisco travel to Starling City to investigate Dr. Wells' auto accident.
Having discovered Dr. Well's secret room Barry and his friends dig into Cisco's subconscious for more intel, and set a trap to try and get Wells to confess to killing Barry's mother. Meanwhile, Eddie tells Joe about a major decision he has reached.
Joe and the Flash tangle with an armored soldier who is targeting the gold reserve, which turns up General Eiling -- and leads to a subterranean confrontation with the super-intelligent gorilla, Grodd.
After Wells reactivates the particle accelerator the S.T.A.R. Labs team is forced to relocate the meta-humans imprisoned there, and Barry reaches out to an old foe for help. Joe pushes Iris away after his recovery from captivity.
Eobard Thawne offers Barry the chance to travel back in time to save his mother, but the consequences may be the loss of the entire world as Barry knows it.
