- "I don't need to heat things up. I need to slow them down."
- —Snart on how he is going to kill the Flash
The Streak 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. With the help of Joe, Barry identifies Leonard Snart as the leader of the group. While investigating the case, Barry gets a surprise visit from an old friend - Felicity Smoak, who heard about his new abilities and came to check them out for herself. 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 Streak and Captain Cold have an epic confrontation.
Harrison Wells tests Barry's ability to multitask by making him play a game of Operation with Caitlin, a game of table tennis with Cisco, and a game of chess with him. Barry easily defeats Caitlin and Cisco, though he makes a bad chess move which causes him to lose against Dr. Wells.
Meanwhile, Leonard Snart and his crew attack a Blackhawk Squad Protection Group truck in attempt to steal the Kahndaq Dynasty diamond, though Barry quickly responds to the scenario, taking down Snart's crew and managing to unmask Snart himself. One of Snart's men loses his cool and shoots a guard, but Barry quickly responds and takes the guard to St. Andrews Hospital. Snart and his crew take the opportunity to escape, but without the diamond. Barry quickly returns to the scene in his civilian clothing and gave Captain Singh his "insight" on what had occurred, stating there were four men who attacked, rather than three, to which Singh sarcastically thanked Barry for. Joe realized that Barry was at the scene earlier and asked if he saw anything that could help to which Barry said he saw the face of one of the men. At the precinct, Barry quickly identifies him as Leonard Snart and Joe notes his father was a dirty cop.
Iris arrives at the precinct with coffee though Joe declines the coffee. Iris tells Barry about the blog she began, documenting sightings of "The Streak". Barry tries to talk Iris out of it, saying it would only bring out crazies and internet trolls. Iris and Barry are then greeted by Felicity Smoak, who has heard of Barry's re-emergence from his coma and decided to pay him a visit.
Meanwhile, Snart reveals to his men that he calculated the time it took the police to arrive. He then blamed one of his men for losing his cool, after which the man quits and Snart kills him. He then stated to those remaining that he needs to identify the "Blur's" weakness.
Barry and Felicity have time to catch up, during which Felicity comes to the conclusion Barry was dating Iris, which Barry quickly denies. Felicity tells Barry she discovered about Barry's powers after overhearing his conversation with Oliver during "Pilot". Barry then demonstrates his speed for Felicity by running to the roof of an apartment building and taking a picture of Felicity and running back in just a matter of seconds. Barry decides to introduce her to his team at STAR Labs, though Felicity has already met Cisco and Caitlin. At first, Caitlin is worried that Felicity will fail to keep Barry's identity a secret, but Barry reassures her by telling the team she works with The Arrow, to which Cisco says everything that happened while in Starling City makes sense now. Felicity is happily greeted by Harrison Wells, who is aware of her accolades and skillset. The team demonstrates how they train and monitor Barry. Felicity begins to question the things that they know about Barry, but Dr. Wells tells her that they are taking care of him.
Eddie and Joe discuss Iris, to which Joe says he didn't care about Eddie's personal life, stating they are strictly work partners and not friends. Barry and Felicity visit Iris at Jitters, where Iris invites them to join her and Eddie for a double date at Trivia Night, despite Barry and Felicity denying any romantic connection between the two of them.
At STAR Labs, a janitor brings Snart both a high powered flamethrower and a gun that freezes its targets. Snart takes the guns and kills the janitor, ensuring that only he knows of the weapon's existance.
At Trivia Night, Felicity arrives in a dress, not realizing that it was a casual event. Meanwhile, Snart takes the tour of the Central City Museum twice in planning to steal the Kahndaq Dynasty diamond, one of the museum's most prized artifacts. Dexter Myles, the curator of the museum, is quickly suspicious of him and contacts Joe, who gathers a force of officers to apprehend Snart.
Back at Trivia Night, Felicity and Barry correctly answer a trivia question for their team. Iris asks Felicity if she has a boyfriend, to which Felicity hesitantly answers no. While Felicity and Eddie take a bathroom break, Iris tries to convince Barry that Felicity is interested in him, citing the way she had dressed and the similarities between her intelligence and Barry's.
At STAR Labs, Cisco realizes that the cold gun has been stolen and alerts Dr. Wells, who is furious at Cisco for creating a weapon, which Wells doesn't want developed in STAR Labs.
Back at the museum, Snart evades Joe's police force and escapes to a nearby theater. Barry rushes to the scene, leaving Felicity to cover for him with Iris and Eddie. Just as Barry arrives, Snart shoots the cold gun at Joe. Barry jumps in front of the shot and pushes Joe out of the way, taking the shot himself. Snart begins shooting the cold gun at innocent civillians to test Barry's speed, and Barry is devestated when he fails to save a security guard.
Upon returning to STAR Labs, Barry learns that the shot from the cold gun had given him third-degree frostbite and that if his cells didn't regenerate the speed they were at, he would've died. Barry notes that Snart wasn't a meta-human but learns that Cisco built the weapon Snart used, which was originally intended to be used on Barry himself. Cisco claims that he made the gun before he got to know Barry, in fear Barry lost control and went psycho like many other meta-humans. Caitlin backs Cisco up, stating he was only taking precautions, but Barry is still angry, mainly because Cisco never told Barry about the gun, which left him totally unprepared and vulnerable.
At Joe's home, Joe tells Iris that the only reason he doesn't want the two be in a relationship is that he fears he'd lose his focus and see Eddie as Iris' lover, rather than his partner. Joe also reveals the fear that she would look at him differently if anything happened to Eddie, because of the work they do, and that he would feel responsible.
Snart reveals to his men that he has discovered Barry's real weakness - the cold gun - but his men turn on him and leave, all the while holding him at gunpoint in case he killed them.
At STAR Labs, Felicity and Barry discuss Barry's anger towards Cisco regarding the cold gun, and Felicity asks Barry to be patient, stating that her own team had a rocky start as well but that their relationship got better with time.
Back at the museum, Snart breaks in and chases off a security guard, stealing the Kahndaq Dynasty Diamond and escaping in the process.
Meanwhile, Cisco discovers a way to track the cold gun by using the city's network and sending a false update, being able to get a signal from the gun in return. Once Felicity hacks into the city's network and a location is determined, Barry quickly suits up, though he disables his communications, stating that he doesn't feel like talking.
The team tracks Snart to the train station, where Joe orders Eddie to stay behind and wait for backup. Back at STAR Labs, Felicity convinces Cisco and Caitlin go and help Barry despite what he said, stating that she had had such experiences with Oliver before. At the train station, Joe is cornered by Snart but saved by Eddie, who states that he was Joe's partner and "not [his] assistant." In the midst of the chaos, Snart manages to board one of the trains, and when Barry arrives on the same train, Snart reveals that his intention wasn't to escape on the train but to derail it, knowing Barry would be distracted by trying to save everyone. After Barry manages to get all the passengers off the train, Snart lands a hit with the cold gun and moves in for the kill. To Barry's relief, Cisco, Caitlin, and Felicity soon arrive with the STAR Labs vacuum cleaner disguised as a prototype of the cold gun, claiming that it was "four times the size, four times the power." The ruse works, and they managed to make Snart surrender, though he gets away with the diamond.
Back at STAR Labs, Felicity says her goodbyes and leaves to return to Starling City, stating that she needed to return to her team. After she leaves, Dr. Wells pulls Cisco aside and tell him to never create anything like the cold gun ever again.
At the precinct, Joe finally begins to accept that Eddie and Iris are dating and supports their relationship.
Meanwhile, Barry chases down the train Felicity is on and the two discuss relationships, where Felicity reveals that though they seem perfect for each other, she is aware of his feelings for Iris, and Barry, in return, assures her that he is also aware of her feelings for Oliver. Barry promises Felicity that if she ever needs his help he will be there in a heartbeat, and Felicity promises him the same. Barry and Felicity then share a kiss before Barry runs off into the night
In the final scene, Snart is seen meeting an old accomplice named Mick Rory, with whom he has done many previous jobs. Leonard states that he needs Mick's expertise and "certain skills", presenting him with a gun that appeared to be similar to his own cold gun, except fire-based. Mick gladly accepts the offer.
- This episode's events take place during The Magician prior to Felicity's return towards the end of the episode.
- This is the first episode of The Flash not to have a flashback story line.
- Felicity's question about Barry running too fast and turning into dust is a reference to Allen's death in Crisis on Infinite Earths.
- The Kahndaq Dynasty Diamond is a reference to Kahndaq, a country in the DC universe best known for being the home of Black Adam, an enemy of Captain Marvel.
- This is the first episode of The Flash where the villain is not a meta-human.
- The concept of precautions being taken in case a hero goes rogue for whatever reason is a common trope in comics. A notable figure who does this is Batman, who in the Tower of Babel storyline had his plans stolen and used on the Justice League.
- When Barry catches up to Felicity on the train he tells her that "Taking the train is still one of the safest ways to travel." She replies "I thought that was airplanes." This is a reference to a quote said by Superman in both the 1978 Superman and 2006 Superman Returns. Both instances he saves a plane from crashing while, in parallel, Barry saves train passengers.
- This episode begins a tradition that episodes featuring Captain Cold in a prominent role have the word 'rogue' in the title. This is a reference to the comics where he was a part of a team calling themselves 'Rogues.'
- Actors Wentworth Miller and Dominic Purcell who play Captain Cold and Mick (Heat Wave) also starred in Prison Break as brothers.
- When Detective West reads out Leonard Snart's name from the mugshot book, Barry says "Leonard? That's almost as bad as Bartholomew." Bartholomew, at least in the comics, is Barry's actual first name.
- One of Snart's cohorts refers to Barry as the Blur. This is possibly a nod to one of the longest running comic book inspired TV shows Smallville.
- When Eddie and Joe are in the car together, "Let's Get It On" by Marvin Gaye plays on the radio as Eddie flips through the stations. In 2006, Jesse L. Martin was originally set to play Marvin Gaye biopic Sexual Healing before it was canned.
- At one point, Joe mentions that Leonard Snart "showed up every six months". It turns out that Captain Cold appears in every sixth episode in season one (aside from a small cameo in the finale)
- When Dr. Wells discovers the missing weapon Cisco tells him that a janitor missed work, which is a reference to parasite a villain from the comics who was a janitor at STAR Labs until he fell into chemicals and went crazy.
- When Leonard Snart's accomplice wants "out" he is shot by Leonard. The gunshot sound is from a gun with a silencer; however, the gun is shown without a silencer attached.
- Barry says that E=mc2 is Einstein's formula for kinetic energy. This is incorrect is the formula is the mass energy equivalence.
- During the trivia competition, Felicity and Barry identify portrait #3 as that of "Erdel". The portrait is clearly that of Nikola Tesla.
- If Felicity and Cisco can hack into the cold gun, why couldn't they just disable it?
- When Dr. Wells, Cisco, and Caitlin discover the weapon has been stolen, the door has a typo in the label reading "Restriced Access"
|The Flash season 1|
|"Pilot" • "Fastest Man Alive" • "Things You Can't Outrun" • "Going Rogue" • "Plastique" • "The Flash Is Born" • "Power Outage" • "Flash vs. Arrow" • "The Man in the Yellow Suit" • "Revenge of the Rogues" • "The Sound and the Fury" • "Crazy for You" • "The Nuclear Man" • "Fallout" • "Out of Time" • "Rogue Time" • "Tricksters" • "All Star Team Up" • "Who is Harrison Wells?" • "The Trap" • "Grodd Lives" • "Rogue Air" • "Fast Enough"|