The episode opens with Barry and Iris leaving a theater. Eddie Thawne calls Iris while Cisco calls Barry. While Iris is talking on the phone to THawne, Barry easily takes care of a goon trying to make a getaway in his car by putting him in the back of the police car. He rushes back just as Iris turns around. He says if she would like to get something to eat as he is famished.
Meanwhile a crime family meets at a restaurant where a bald man locks them in the restaurant. The crime family is suddenly wiped out by a green gaseous cloud. At the crime scene, Joe and Barry figure out that the poison would have had to be inside the building as the doors dare latched from the inside. Barry suggests that they were being attacked on by one.investigate the scene of the crime and
S.T.A.R. Labs discovers that the meta human that can control toxic gasses.
Joe proposes that STAR Labs figure out a way to imprison all of the meta human villains as a normal jail would not be able to hold meta humans.
Caitlin has a flashback to the night that the particle accelerator was turned on. We are introduced to Ronnie, Caitlin’s fiancé. Both are making honeymoon plans, and the mood is a celebrators the STAR Labs crew all begin to celebrate. Wells pops some champagne where the champagne is suspended in the air before spraying all over. Suddenly there is a loud bang and an alarm goes off.
Instead of going to the particle accelerator with Wells, Barry sees that Caitlin is visibly shaken and asks her to come to the police station to help with the metahuman investigation. Everyone at his day job treats him like he’s a joke and take him for granted. He uses his powers and delivers a report to his superior who is somewhat impressed but tells Barry to clean his lab.
Joe sits at home and watches a past interrogation Henry Allen. Henry tells joe that he is not a killer, and that Joe should speak up and tell everyone that he needs to speak up for Henry. Iris walks through the door as Joe quickly shuts his computer explaining that he’s working on”work stuff”. Thawne comes to visit Iris but notices that Joe is there to which he covers by asking Joe to come back to the restaurant so they can investigate gain.
Cisco has a flashback where the team is trying to shut down the accelerator. Ronnie says that he will shut it down manually. He tells Cisco to close the shielded doors and save the others if Ronnie wasn’t back in two minutes, which Cisco agrees to do after Ronnie tells him that saving Caitlin was more important
Caitlin and barry talk about Ronnie as Barry wants to learn more about him. We learn that he was a Structural Engineer for the Particle Accelerator. Caitlin states that they were like “fire and ice” (Ahhh I see what you did there, ya know because Ronnie becomes Firestorm). Caitlin and Barry learn that the meta human doesn’t control gas, he becomes the gas! Meanwhile at a mall a woman gets onto an elevator while talking to her daughter on the phone. The bald man we saw earlier at the restaurant steps in the elevator as the woman looks at the man in horror as she recognizes him. He turns into the mist and kills a woman who appears to be a judge who sentenced him to death.
Barry races to the scene and finds the bald meta human trying to escape. After a short battle barry is subdued as the man turns to gas and flows into Barry’s nostrils and mouth. Barry begins to suffocate as he is poisoned, but manages to make it back to S.T.A.R. Labs and is treated. Cisco seems to name all of the villains they face and dubs the gaseous meta human “the mist”. Barry meets with Joe to talk and reveals that he can’t deal with the fact that he could not save the judge. He toys with the idea of breaking his dad out of jail, but Joe tells him that his dad will be on the run for the rest of his life. If they want to get Henry out of jail, they need to do it the right way. Barry learns that you can’t avoid pain and you can’t save everyone.
The police receive tons of calls about a “red streak”. Iris tells Eddie that she has never had a real boyfriend, but somehow she cannot . he kisses eddie.
At the police department, Thawne is answering calls about a “red streak” at the mall attack site. Iris shows up and tells Thawn that she’s going to tell her dad about their relationship. By doing this, it will make their relationship “real”.
Caitlin and Barry talk about the losses in their lives. He offers to go down to the lower level with Caitlin as she has another flashback. She insists that Cisco open the door, but its too late as the door is sealed. Ronnie ends up saving everyone by redirecting the particle beam so that it will be aimed up and not out. Caitlin is upset at the fact that nobody will know what he did, and Barry tells her that he knows, and that Ronnie died a hero.
Back at the lab, the team learns that the mist is known as Kyle Nimbus. He was a prisoner sent to death via the gas chamber the night the particle accelerato exploded. So naturally the gas became his ability.
Joe visits Barrys father Henry Allen at Iron Heights prision, where Nimbus prepares to walk into the facility. Barry calls Thawne as he cannot get a hold of Joe. He learns that Joe is at Iron Heights. Joe reveals to Henry that he knows that he did not kill his wife Nora, and that he is going to reopen the case. Nimbus appears in front of Joe at the prison and poisons him for pursuing and arresting him in the past. Barry races to the prison to save Joe with an antidote. Once he sees that Joe is stable, he goes after Nimbus.
Barry realizes that he cannot battle Nimbus so he avoids him at all cost. He he can wear out Nimbus’s gas abilities, which he does and subdues him.
Joe recovers in the hospital as Barry sits by his side. Barry reveals to Joe that he was right, that breaking Henry out of jail was not the right way. Eddie and Iris show up at the hospital to which joe figures out that they are dating. (didn’t take a genius to see that coming!)
S.T.A.R. Labs imprisons Nimbus in a containment pod located in the particle Accelerator’s area 52. Nimbus turns to gas which has no effect on his metahuman prison, he is trapped and the containment pod is working. Caitlin seems uneasy working above a Metahuman prision, but Wells tells her that she will get used to it. Cisco feels responsible for Ronnie’s death and tries to apologize to Caitlin, but she says that he doesn’t need to. That she is fine and that she loves Ronne even more remembering what he sacrificed.
The episode ends as Dr. Wells has a flashback to the night the accelerator blew up. He walks to his secret room and watches Barry about to be hit by a bolt of lightning where He says “see you soon, Barry”.
Overall it was a great episode, probably the best yet! I am very curious who Wells truly is. It’s obvious that he is from the future and seems to have Barry’s best interest in mind….or does he? He has already killed a man for inquiring about Barry. I’m starting to think that he is Reverse Flash/Professor Zoom. I guess we will find out soon enough!