- "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. Joe shows Barry a book of suspects and 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.
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. Barry knocks down Snart's crew and manages to unmask him. One of Snart's men loses his cool and shoots a guard. Barry quickly responds and takes the guard to St. Andrews Hospital though Snart and his crew took 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.
Leonard reveals to his men that he calculated the time it took the police to arrive. Leonard then blamed one of his men for losing his cool. The man quits and Leonard kills him. Leonard then stated to those remaining that he needs to identify the "blurs" weakness.
Barry and Felicity had time to catch up, to which Felicity had the impression Barry was dating Iris. Felicity told Barry she discovered about Barry's powers after overhearing his conversation with Oliver. Barry then showed Felicity his power, 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 then decides it's alright to introduce her to his team, though Felicity has already met Cisco and Caitlin. Caitlin at first is worried that Felicity will fail to keep the 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 and asks Barry if he knows who The Arrow is but Barry avoids the subject. Felicity is soon greeted by Harrison Wells, who is happy to meet Felicity, being aware of her accolades. The team then show how they train and monitor Barry. Felicity then begins to question things that they know but Harrison tells her that they are taking care of him.
Eddie Thawne and Joe discuss about Iris to which Joe said he didn't care to discuss about Thawne's personal life, stating they are strictly work partners and not friends. Barry and Felicity visit Iris at Jitters where Iris invited them to join her and Eddie for Trivia Night. When Felicity called her work to check in, Iris told Barry that she should ask Felicity out, though Barry told Iris they're only friends.
A janitor from S.T.A.R. Labs brought Leonard both a high powered flamethrower and the cold gun, though Snart killed the janitor.
At Trivia night, Felicity arrived in a dress, not realizing that it was a casual event. Meanwhile, Leonard took the tour of the Central City Museum twice in planning to steal the Kahndaq dynasty diamond. Dexter Myles was quickly suspicious of him and contacted Joe. Back at Trivia night, Felicity and Barry correctly answer a trivia question for their team. Iris asked Felicity if she had a boyfriend and Felicity hesitantly answered no. While Felicity and Eddie took a washroom break, Iris told Barry that she believed that Felicity was interested in him based on how she dressed and answered her question.
At S.T.A.R.Labs, Cisco realized the cold gun had be stolen and Wells was furious at Cisco for creating a weapon which Wells does not believe belongs in S.T.A.R. Labs. Wells ordered Cisco to track the gun immediately.
Back at the museum, Leonard quickly realized Joe was on to him and moved to a nearby theater. Barry quickly responded to the scenario and Felicity covered for Barry. Snart moved to a nearby theater and shot the cold gun at Joe. Barry jumped in and pushed Joe out of the way in time though he was shot himself. Snart began shooting the cold gun at others to test Barry's speed where Barry failed to save a security guard.
At S.T.A.R. Labs, Barry learned that if his cells didn't regenerate the speed they were at, he would've died from the third degree frostbite. Barry noted that Snart wasn't a meta-human but learned that Cisco built the weapon Snart used which was intended to be used on Barry. Cisco claimed he made the gun before he got to know Barry, in fear Barry lost control and gone psycho, such as the other meta-humans. Caitlin backed Cisco up, stating he was only taking precautions though Barry was still angry due to the fact that Cisco never told Barry about it, which made him unprepared.
At Joe's home, Joe revealed to Iris the only reason he doesn't want the two be in a relationship is that he fears he'd lose his focus as he would see Eddie as Iris' lover, rather than his partner. Joe also told Iris he'd fear she would look at him differently if anything happened to Eddie because of the work they do and he would feel responsible.
Leonard revealed to his men he discovered Barry's real weakness, though his men turned on him and left him, holding him at gun point in case he killed them.
At S.T.A.R. Labs, Felicity told Barry, despite Cisco originally not trusting Barry, to be patient as her team took time to get together.
Back at the museum, Snart broke in and chased off a security guard, stealing the Kahndaq Dynasty Diamond in the process.
Cisco discovered a way to track the cold gun, by using the cities network and sending a false update, being able to get a ping back. Cisco claimed it should take half an hour, though Felicity took a few seconds. Barry quickly suited up, though he shut down his communications, stating he didn't feel like talking.
At the train station, where they tracked Snart, Joe ordered Eddie to stay and wait for backup. Back at S.T.A.R. Labs, Felicity told them to go and help Barry, despite what he said as she had such experiences with Oliver before. At the train station, Joe was saved by Eddie from Snart though Snart managed to hop on the train. When Barry arrived on the same train, Snart told Barry the intention wasn't to escape on the train and to derail the train, knowing Barry would save everyone. After Barry got all the passengers off the train, he was struck by Leonard with the cold gun. Cisco, Caitlin, and Felicity soon arrived with the S.T.A.R. Labs vacuum cleaner, claiming it was the prototype cold gun. They managed to make Leonard surrender, though he got away with the diamond.
Back at S.T.A.R. Labs, Felicity said her goodbyes and left to return to Starling City. Harrison then told Cisco to never do anything as to build such a weapon again.
At the precinct, Joe finally begins to accept the relationship between Eddie and Iris and supports their relationship.
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 tells Barry that she is aware of his feelings for Iris and Barry in return reveals that he is also aware of her feelings for Oliver. Barry then reassures Felicity that if she ever needs his help he will be there in a heartbeat and Felicity assures him the same, Barry and Felicity then share their first kiss before Barry runs off in the night.
Leonard later is seen meeting an old accomplice, Mick Rory who he had done many robberies with before. Leonard stated that he needs Mick's expertise and skills and presented him with a gun that appeared to be similar to his cold gun, except fire-based. Mick gladly accepted the offer.
- 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.
- The man at the end of the episode is Mick Rory. Otherwise known as Heatwave and is a member of the rogues.
- Snart mentions a sister. In the comics, Len Snart has a sister, Lisa, also known as the Flash rogue, Golden Glider.
- 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 Harrison discovers the missing weapon Cisco tells him that a janitor missed work, this is a reference to parasite a villain from the comics who was a janitor at S.T.A.R labs until he fell into chemicals and went crazy.
- This episode's events take place during The Magician prior to Felicity's return towards the end of the episode.
- 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 as "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"|