After using the thinking cap with Dark Matter, Harry realises the devastating effects he has caused damage to his brain and will have to re learn everything he has ever known.
Barry and Iris attend a therapy session with Dr Finkle who quizzes Barry about his feelings after Ralph’s death. Barry is very shut down emotionally and believes it is just because he has dealt with a lot of death.
Cisco approaches Harry with the idea of him having a thinking cap as well but Harry knowing his own outlook after using his cap tries to put Cisco off.
A pocket dimension opens close to the location of Nuclear Meta Human Fallout, fearing DeVoe is after him team Flash make a plan to move him. As Catlin has lost the ability to become her alter ego Killer Frost they decide to open a breach to Earth X to collect Leo Snart to use his cold gun in transportation as a back up along with a cold suit. They collect him just in time as he was just about to be attacked by Siren X who was angry about the deaths of her team of villains.
After reluctantly building Cisco a thinking cap he over powers it to break it, telling Cisco the source to mend was unavailable to put him off pursuing it.
Over at DeVoe’s lair Marlize is having a tough time with her power crazed husband. She wears what used to be his favourite dress of hers which causes him to belittle her saying it is an unwelcome distraction and next time she shouldn’t even think.
Leo Tries to talk to Barry about how he needs to grieve, which seems to fall on deaf ears.
During the transportation of fallout a pocket dimension opens and the transportation truck is lifted in to the air by DeVoe using Nulls powers. Barry uses Harry’s supercharged the tuning fork on DeVoe who counteracts the power by using Ralph’s powers and elongates which is a shock to Barry. Siren X then turns up and Barry is unable to react after seeing his old friends powers being used and she takes Fallout, Joe and Caitlin captive and makes DeVoe flee.
DeVoe returns to his Lair very angry as for once he hadn’t foreseen the outcome which Marlize points out is because he doesn’t understand emotion.
Cisco finds the rare souce to power the thinking cap and wants to re attempt using it so Harry has no choice other than to come clean about how it has affected him.
Siren X takes fall out to CCPD and removes his helmet from his cooling suit causing him to overheat. after a few failed attempts to take her down Barry has a flashback of Ralph’s Last moments and finds the power to defeat Siren X and cool Fallout back down and transport him to safety.
Barry goes back for another therapy session and finally confronts his grief for Ralph.