With only one Bus Meta remaining - the radiation emitter called Fallout - Barry needs help moving him to a more secure location where The Thinker can't get him. This calls for the help of an unexpected ally and who could be more unexpected than Citizen Cold - Len Snart's heroic counterpart from Earth X? Unfortunately, when they retrieve him, the Nazi Black Siren of Earth X comes along for the ride. Meanwhile, Cisco begins to grow suspicions regarding Harry's use of The Thinking Cap as Harry is reluctant to let him build a second one.
Mad Max: Fury Road (title and general chase theme)
For the past few episodes, Cisco was the one character warning everyone else about how dangerous The Thinking Cap was. Now, suddenly, he's all about using it and wants to use it himself.
Apart from needing Black Siren on the loose to add a further complication to this episode, there is no good reason why Barry couldn't have taken out Black Siren before he and Citizen Cold left Earth X.
Despite having an apparent mad-on for everyone involved in overthrowing the Nazi Regime on Earth X - especially Citizen Cold (whom she followed to another Earth just to kill him) - she is content to just take Citizen Cold's cold gun and leave him and The Flash unconscious in a gutter rather than shooting them with the cold gun, blasting them with a Sonic Scream or doing... well, anything that would result in them dying!
Why isn't Black Siren incapacitated by Fallout's radiation?
See The Boomerang Factor for details how the heroes were made ineffectual during the final fight with Siren-X.
One big question this episode raises that will probably be ignored by The Flash and Arrow - doesn't the capture of Siren-X pretty much screw up Black Siren's efforts to pose as Laurel Lance? She made a rather big show of coming back to Star City claiming to be held captive for two years and now a metahuman who looks just like her shows up trying to blow up a police station in Central City? That should attract attention and raise questions that Joe can't deflect. We know Snart didn't take Siren-X back to Earth-X with him, so where is she? Did ARGUS take her? Is she in The Pipeline? We don't know! But someone should have noticed a second evil Laurel Lance running around Central City.
Wentworth Miller. 'Nuff Said!
The title of the episode is a pun on the movie Mad Max: Fury Road.
Katie Cassidy - who plays Black Siren on Arrow - appears playing the Black Siren of Earth X, aka Siren-X.
Apart from being a literal Nazi and having super-hearing powers and wearing a mask, there doesn't seem to be any difference between Siren-X and her Earth Two counterpart. Citizen Cold says that she's the only surviving member of The Reichsmen. An elite assassin gone mad, she had an unrequited love for The Dark Arrow, and is out to kill everyone involved in his death - Citizen Cold especially.
Iris says that ARGUS has a secure facility in New Brighton that should be able to contain Fallout and keep him safe. In the DC Comics Universe, New Brighton is a borough in Central City that is primarily residential and commercial in nature, housing the main Central City Rail Station.
In the DCTVU, New Brighton is a city on the other side of the state from Keystone City.
The excessive infusion of Dark Matter into Harry's neural system has disrupted the area of the brain where general intelligence and executive function occur. This is inhibiting his ability to integrate new information, or, in simple terms, Harry is losing his intelligence and will eventually need to relearn everything he ever learned.
The Thinker has not suffered any decline in his metabolic processes since his transference into Ralph's body. He claims that Ralph's elasticized cells could contain the power of another bus full of metahumans.
The Siren-X can use her powers to disrupt a Vibe portal long enough to hold it open so she can use it before it closes.
Caitlin is working on a modified radiation hazmat suit to keep Fallout's core temperature from rising to the point of detonation.
Harry blames the failure of the second Thinking Cap on a hyper-limiter valve.
Cisco notes that the second Thinking Cap was made with promethium ion diodes. Harry claims these probably overloaded the cap as well.
Caitlin created a cocktail of atomized DTPA and potassium iodine. With any luck, if the Fallout containment suit fails, the solution should flood the thyroid with enough non-radioactive iodine to offer them some protection from the radiation. This protection will only last for 2-3 hours.
The Fallout suit also prevents Fallout from being tracked by satellite due to his radiation signature.
Caitlin's tests determine that there is still a cryogenic anomaly in her DNA even without any traces of Dark Matter. This means that there is still a trace of Killer Frost inside her - she just has to figure out how to get her to appear.
(The Thinker pulls up a display for some manner of device.)
The Mechanic: We start today?
The Thinker: Yes.
The Mechanic: But we have time, my love. Could we not spend time together? (purring) As husband and wife? I think
The Thinker: Mmm. That is... that is your first mistake. Leave the thinking to me.
Citizen Cold: War's over. Bad guys and girls lost. Nazi regime's been dismantled. And The Rebellion's in charge now. Why don't you turn yourself in? Save us the Tom and Jerry? Find some other misguided cause to get all aggro about?
(Cold hears and noise and fires a blast too late, being knocked to the ground by a sonic blast.)
Siren-X: Not this night. I will fight until every last one of you finds the same fate as my brothers and sisters.
(Before Siren-X can finish him off, there is a golden burst of lightning as The Flash carries Citizen Cold off to where Vibe is waiting on the far side of the room.)
Citizen Cold: Your timing is impeccable.
The Flash: We need your help on our Earth.
Citizen Cold: Right now? I'm kinda busy.
Vibe: With what? Dying?
(Citizen Cold turns around, toward the sound of Black Siren's footsteps.)
Citizen Cold: Touche.
Citizen Cold: So. You're trying to stop a guy who thinks he's smarter than everyone and his true-believer lover, who are hell-bent on achieving their evil machinations at any cost? (pause) Well, that's right up my alley!
Barry: Winning this battle might just win us the war.
Citizen Cold: Here here! Let's all make sure we keep our heads in the game, so we can stay safe out there.
(Everyone else breaks up as Barry walks up to Snart.)
Barry: I know what that was about.
Citizen Cold: It was a good speech, Barry. Just making sure you heard it, just didn't give it.
Barry: What's that suppose to mean?
Citizen Cold: If you don't confront your feelings, they will confront you.
(Caitlin explains how she's adjusting to Killer Frost not leaving her post-it notes anymore.)
Citizen Cold: Do you miss her?
Caitlin: It's not that. It's just that... we were starting to become close lately. And I know how crazy that sounds considering we're talking about someone who actually lived inside of me!
Citizen Cold: I'm on an alt-Earth transporting a human bomb with an escort who can literally run back to the future. Your story is the least crazy thing I've heard all day.
(Citizen Cold is explaining everything he knows about Siren X.)
Iris: So she has the same powers as Black Siren?
(Citizen Cold looks confused.)
Iris: The Laurel Lance of Earth Two.
Citizen Cold: And Earth One's Laurel Lance?
Barry: She died.
Cisco: She was the second Black Canary after her sister.
(Citizen Cold looks confused.)
Cisco: Who also died and came back. But as White Canary. Because-
Cisco: ... it's complicated.
Cisco: Harry, how could you be so stupid?
Harry: 'Cause I felt so stupid!
Cisco: We all feel stupid right now!
Harry: Yes, but you're Vibe! Allen's The Flash! Who am I? My only job is to be smarter than all the villains who want to hurt this team and without that I'm nothing! I am about to lose the only part of me that has any value to this team. The only part of me that matters! And so, yeah! I destroyed The Cap! So you wouldn't make the same mistake I did.
The Mechanic: You really don't see it?! You can calculate near-infinite outcomes across multiple Earths, but you cannot account for how someone is feeling?
Citizen Cold: Barry, trust me. There's no outrunning grief. (pause) That was a pun. I'm sorry.
Citizen Cold: Well, look at that. Something old. Something new. Something borrowed. Something... navy.
Black Siren X: A nuke is a terrible thing to waste.
Black Siren X: CCPD. Home of the brave. Land of the dead.
Harry discovers that using the Dark Matter powered thinking cap has damaged his brain's ability to absorb new information and will eventually erase his mind completely.
Barry and Iris go to see Dr.Sharon Finkel about Ralph's death.
Iris still has her arm in a sling following her injuries in the last episode.
The Mechanic is happy without needing to be drugged, much to The Thinker's surprise. She credits this to it feeling like he had gone away when he was in the other Bus Meta bodies.
Cisco has the idea to build his own Thinking Cap. Harry reluctantly agrees to help him with it.
Tracy Brand's lab is revealed to be in Keystone City.
Team Flash decides to retrieve Citizen Cold from Earth X, as they can use his cold gun to keep Fallout from going into a nuclear meltdown.
Citizen Cold last appeared in L310.
We discover that the Nazi regime on Earth X has been overthrown. The Rebellion is now running the world government and is in the middle of cleaning up the Nazis, like Black Siren, who refuse to surrender.
Citizen Cold did propose to The Ray, as he said he would during his last appearance. They are getting married in one day.
The plan is to transport Fallout in the special suit Caitlin made, with Leo Snart's cold gun as a back-up to keep Fallout's temperature down, to a special ARGUS facility in New Brighton.
According to Cisco, the Thinking Cap inspires a tingling feeling like his conditioner working when active.
The Mechanic wears The Thinker's favorite dress to please him. He tells her to change into something more appropriate.
Highway 14 is the most rural route between Keystone City and New Brighton.
18,322 rebels died fighting the Nazis on Earth X. 3,679 were under Citizen Cold's watch.
Neil Borman (aka Fallout) makes his first appearance since 410.
The Sonic Scepter is not powerful enough to disturb The Thinker in Ralph's body. He is, however, affected by Black Siren's sonic blasts.
Harry finally confesses to Cisco that he used The Thinking Cap while it was powered by Dark Mater.
The Thinker predicted everything that happened in his confrontation with The Flash and Citizen Cold - even the arrival of Siren-X. The only thing he did not account for was Barry freezing up at the reminder of Ralph's death.
Siren-X tries to use Fallout to blow up CCPD HQ.
Fallout is taken into custody by ARGUS and moved to a different off-the-grid black ops site.
It is unclear what happens to Siren-X. Leo Snart doesn't take her with him when he returns to Earth-X, so presumably ARGUS took her into custody as well.
Cisco invites all of Team Flash to his wedding.
Cisco gives Leo Snart a Inter-Dimensional Extrapolator, identical to the one he gave Supergirl, in case Leo ever needs to travel to Earth One.
Leo Snart also takes the spare costume belonging to Captain Cold.
Harry agrees to tell the team about his losing his intelligence, but not today.
Barry makes another appointment with Dr. Finkel to discuss Ralph's death.
Earth X - An Unnamed Warehouse
Tracy Brand's lab in Keystone City
Highway 14, between Keystone City and New Brighton.
The Fridge Factor
Even on a world where she's a born and bred Nazi super-villain, Laurel Lance still isn't free to be evil on her own terms, driven crazy by her unrequited love for Oliver Queen. Yay co-dependence!
The Boomerang Factor
Barry could have easily taken out Black Siren when they came to pick up Snart from Earth X. But since she's needed to add tension to the story, he didn't.
Tasked with finding a truck on a remote rural freeway, it never occurs to Barry to... run along the freeway and see if he can catch up to it. This becomes even more maddening when it turns out that Siren-X drove the truck back to Central City where Cisco's usual tracking software should have found it long before she got to CCPD HQ.
Barry somehow manages to run head first into a sonic-blast.
Caitlin grabs a hold of the cold gun that Siren-X dropped... and uses it on Fallout, who is already being blasted by Citizen Cold, instead of the unoccupied Siren-X.
The Bottom Line
Proof that even a Wentworth Miller guest spot can be spoiled by the inclusion of Katie Cassidy. It's not all bad but the sad truth is that Siren-X's role in this episode feels entirely tacked on and only serves to cause the rest of Team Flash to be dumbed down to accommodate her cartoonish antics.
It's a crying shame though because there are so many scenes that are magical, particularly Citizen Cold's interactions with the team. Though this is reportedly going to be Wentworth Miller's final adventure as any version of Leonard Snart, the door is left wide open for his return if his schedule frees up enough. Unfortunately, the fate of Siren-X is also left open. (In fact, they don't even bother saying what happened to her!)