Inspired by the revelation of Zoom's true identity, Barry becomes more determined than ever to find a way to increase his speed without turning to the Velocity drugs. This leads Barry to travel back in time to seek the help of the one person who knows how to train as a speedster - The Reverse Flash, Eobard Thawne! But the universe has ways of dealing with time-traveling speedsters and Barry will have to outrun the so-called Time Wraiths while trying to avoid further damaging the time-line.
The Black Flash storyline from The Flash comics of Grant Morrison and Mark Millar (introduces an Angel of Death that targets speedsters, similar in appearance and abilities to The Time Wraiths), The movie 12 Monkeys (name dropped by Cisco, plot involves someone time-traveling to the past in order to find out information to prevent a future disaster), Flashpoint (The Flash inadvertently changes his present after changing the past), Harry Potter and the Prisoner of Azkaban (name dropped by Cisco and Pied Piper, The Time Wraiths physically resemble The Dementors) and the Doctor Who episode Father's Day (the continuing theme of time-travelers altering their present after traveling to their past and the Time Wraiths resemble The Reapers in function, destroying time-travelers who damage the time line.)
You'd think Barry would have learned his lesson about altering the past by now. Granting that he has to improvise a bit when he arrives too early, that still doesn't excuse his thwarting Pied Piper's escape.
As usual, Tom Cavangh steals the show as he plays Eobard Thawne once again. And in his final scene as Harry Wells.
Grant Gustin gets some great moments here as well, both playing against himself and in his battle of wits scene opposite Tom Cavangh. And the final scene with Iris is Gustin at his sweetest ever as Barry Allen.
The fight sequence between the two Flashes is nicely handled.
The script is well-written, with a perfect balance of humor, action and drama.
As the episode opens, Barry is hard at work on developing a Speed Equation that will boost his powers. This is a reference to the mathematical formula recited by the speedster heroes Johnny Quick and his daughter Jesse Quick to access the Speed Force.
Later in the episode, when Barry, Caitlin and Cisco are looking at the information Thawne gave to Barry, the speed formula - 3X2(9YZ)4A - is visible at several points in the hologram.
Thawne identifies the ghost that is chasing after Barry as a Time Wraith - a being that exists to destroy speedsters who travel in time and alter the timeline before they can cause serious damage. The Time Wraiths - in appearance and power - appear to be similar to The Black Flash. The Black Flash is a being in The Flash comics who is basically an angel of Death for speedsters, trying to grab them and draw them into The Speed Force.
Cisco refers to the Time Wraith as Inky - one of the ghosts from the Pac-Man video game.
Piper's reformation in this episode is not without precedent. In the original comics, Pied Piper was the first of The Rogue's Gallery to reform and become a part-time superhero. He primarily worked as a social crusader who fought for the poor and needy. He also outed himself as homosexual and became a vocal LGBT activist, noting the irony of his being the first Rogue to "go straight".
Caitlin determines that The Flash, Reverse Flash and Zoom all move their legs at essentially the same speed. What allows Zoom and Reverse Flash to move faster than Barry is their feet spending less time on the ground between strides, which propels them forward at least 30% faster.
Wally's adviser wants him to help her with a project based around pushing the speed limits of smaller propulsion systems.
Thawne advises using sound stimuli in Pied Piper's cell to counteract his tinnitus after removing his hearing aids.
Time Wraiths only go after time-travelers and speedsters who do not know what they are doing, according to Thawne.
Pied Piper is able to drive off the Time Wraith by projecting a certain frequency through all the speakers in the cells of the STAR Labs Pipeline. He theorizes an exact frequency could cause the Wraith to dissipate.
Cisco is unable to repair Pied Piper's gauntlets. The electron guns are fried and the battle with The Flash shorted the wave tubes and destroyed the amplifiers. Cisco also doesn't know how to manipulate the frequency variance.
Thawne says the key to increasing Barry's speed is tachyon enhancement.
In the present day, Piper is able to disperse the Time Wraith by using a sonic blast that is low in frequency and high in intensity.
Barry: I let it happen again. I trusted someone I shouldn't have. Jay Garrick. Zoom. Just like I trusted Harrison Wells. Or Eobard Thawne. You see what I mean? I made the same mistake twice. I thought they wanted to teach me how to use my powers, train me to get faster. But they didn't come here to help me. They came to use me. And take everything I love away from me. But no more. I'm going to crack the code, figure out how to improve my speed. I'm going to train harder, get stronger and run faster than anyone's ever run before. And then I'm going to stop Zoom.
(Regarding The Time Wraith)
Barry: Can you track it?
Cisco: What is it with you guys? It's liek you all think I have ESP or something. I can't just magically sense where things are!
Thawne: Have a seat.
Barry: Is this about the speed equation?
Thawne: As a matter of fact, it is.
Barry: (sitting down) Oh, great! Okay. Good. So you figured it out?
(Thawne stands up from his wheelchair and strikes Barry across the back of the head, knocking him out.)
Thawne: Yes. I figured it out.
Barry: The Speed Force. You manipulated it. How did you do that?
Thawne: (pacing around the room) No. (pauses) No, no, no, no, no, no, no. Nooooo. You'd only come here if something went wrong. If you're still alive, then that means... I haven't beaten you. If you're still alive. ..That means my plan fails. And it my plan fails (throws chair) I don't get to go home and if that's the case...
(Thawne begins vibrating his hand at super-speed and lowers it to Barry's head)
Barry: No! No! No! Hey! Hey! Hey! It's the opposite! You trick me. You harness my speed. We turn on the accelerator and create a path for you to go home. I go back in time. You go back to yours. You won!
Thawne: Then why are you here? Why are you here now?!
Barry: Because when I got back a singularity had formed. And now the only way for me to learn how to get faster and stop the singularity from happening was to come here. Now.
Thawne: Well that's good to know. (sighs) There's just... just one thing that occurs to me. I don't need you. Do I? Not THIS you, certainly. Oops! You probably should have thought of that before you came here. Shame... (laughs) You ran all the way back here just to die.
Barry: You kill me, Barry... this Barry - your Barry? He learns it all. There's a hidden letter telling him how it ends. How to beat you. Everything. Anything happens to me? You never make it back home.
(Thawne just stares at Barry)
Barry: Go on. Kill me Thawne. See how this all ends.
(Thawne paces around the room and then sits back down)
Barry: Now, you're going to help me get faster.
It's a quick moment but Cisco's playing Rick Astley's Never Gonna Give You Up through the speakers of Piper's cell and staring at him expectantly is a nice gag.
Past Barry: Okay. So I'm - who are - who are you?
Caitlin: Who is he? Who are you?!
Past Barry: What do you - I'm Barry. I'm Barry! Your Barry! He's -
Cisco: Your doppleganger!
Barry: No. Not yet. I am you, Barry. Just... different.
Cisco: Wait a second - how do we know which one's the real Barry?
Past Barry: Dude! Okay. I've watched Wrath of Khan with you like five times.
Cisco: (pointing to Barry) Impostor!
Barry: Yeah. And every time, at the end, you turn to me and you say, "I have been and always shall be your friend."
Cisco: (the hand pointing at Barry makes the Spock gesture as Cisco points at Past Barry with his other hand) Haha! You impostor!
(Caitlin just squints at Past Barry, shaking her head as Cisco points to both Barrys and looks confused)
Cisco: What is going on here?
Barry: Okay guys. I'm sorry. This was not supposed to happen. The tranq dart that Caitlin made was supposed to last a lot longer.
Caitlin: I did -NOT- give him a tranq dart.
Barry: Okay, no, yes. Not you. The you from the time that I am from.
Past Barry: The time that you are from?
Thawne: I think what he's trying to say is he's from the future.
Past Barry: The future?
Past Barry: The fu-
Past Barry: Wait, the fu-
Past Barry: Are we saying I can time-travel?
Barry: One day.
Cisco: Oh. That explains the white on the symbol. But wait a second. Suppose we now change your emblem, because we got the idea from this. Or, I mean, that would mean...
Thawne: (to Cisco) Stop talking (to Barry) You stop talking too.
Harry: I don't know what I've done.
Barry: You did what you thought you had to do. You risked your life to save her. You brought her here to protect her from Zoom. You acted like a father.
Harry: Like a father. You know, my wife had to... talk me into having kids. Kids. They're small, loud, run around... All I needed was my science and my job for my joy and happiness. And then... the moment we had her, all that I wanted was... her love. Now? I wonder if I'll ever see that again.It seems every decision I've made lately has backfired on me.
Barry: You just have to trust that in the long run you made the right ones.
Eddie: What does Iris mean to me? Wow. You know, a lot of times I have a hard time figuring out what to say to people. But when it comes to you, Iris, I don't. Because with you, everything that used to feel tough just doesn't anymore. It's one of the things I love about you. You don't need me. You can handle anything on your own, because...you're fearless. And independent. Loving. Kind. You are, without question, the best decision I ever made, Iris West. And I never thanked you for choosing to be with me. Because each day with you is a gift. So, thank you. You deserve the world, Iris. You deserve to be happy. And nobody wants that more for you than me. Happy Birthday, baby! I love you.
Barry: Sometimes the only way to move forward is to revisit the things in the past that were holding you back. You have to deal with them head on, no matter how scary they may be. Because once you do, you'll see that you can go further than you ever imagined.
Cisco has another vision of Zoom dangling a woman over a roof-ledge when he approaches Jay Garrick's helmet.
Cisco refers back to the events of 213 and how well Barry impersonated himself on Earth 2, when Barry suggests going back in time one year and pretending to be his old self.
Barry refers to how he saw his mother's death in 123.
Barry travels back to the time of 111, just as he was first fighting The Pied Piper.
As Barry is running to the past, we see visions of The Singularity opening and Eddie Thawne getting shot (123) and his second fight with Pied Piper (111).
Barry's first change to the past comes when the comms on his cowl cause interference due to his proximity to his past self. This interference is noticed in STAR Labs, and forces Barry to more directly take out his past self to deactivate his comms.
Barry's second change comes when he warns Cisco about Pied Piper's hearing aids also being potentially explosive. This prevents Piper from escaping as well as his second battle with The Flash from occurring. This leaves Piper in his cell when the Time Wraith first attacks STAR Labs and he is able to use his gauntlets to drive it off.
Thawne says they'll make Piper some non-explosive hearing aids that will treat his condition. This may be what leads to the changed timeline in the crossover episode with Supergirl (S118), where Barry is able to create ear-pieces that counter the abilities of Silver Banshee.
While in the past, Barry has Eddie Thawne record a special message for Iris, so he can give it to her in the present just before the anniversary of his death.
The third change Barry makes is in revealing himself to Cisco and Caitlin, after his past self recovers from the tranquilizer much faster than expected.
The fourth change Barry makes is telling Cisco to ask Pied Piper about Ronne Raymond, since the chance Cisco had for Piper to bribe him with the information won't happen in the altered timeline.
In the altered timeline, Pied Piper is reformed and reconciled with his parents. He also knows Barry's secret identity and is apparently on friendly terms with the STAR Labs team.
Harry Wells is still trying to find Jesse as of this episode.
Harry says it's easier to find a two-ton gorilla on Earth 1 than a teenage daughter, in reference to 207.
Thawne refers to having met other speedsters besides Barry Allen.
The Fridge Factor
Caitlin briefly mentions that she wants to stop Zoom as badly as Barry does. It's good that they mentioned it, but it still seems like they are brushing the fact that Caitlin's trust in Jay Garrick was abused far more than Barry's. As betrayed as Barry feels by having had yet another mentor betray him, that's nowhere near as serious as Caitlin being romanced by a super-villain who was lying to her from day one.
The Boomerang Factor
Again, Barry totally forgets his previous experiences attempting to alter things in the past or in an alternate reality. This time, however, things seem to work out for the better, with Pied Piper now apparently an ally of Team Flash in the present.
The Bottom Line
A great episode, flawed only in that we could have used some more time to establish how things changed with Pied Piper. It's still one of the best episode of the series ever.