Arrowverse Wiki
Arrowverse Wiki
"Ralph! Just fight it, alright? Fight it. I'll save you."
"You already did, Barry."
Barry begs Ralph not to be taken over by The Thinker

"Lose Yourself" is the eighteenth episode of the fourth season of The Flash, and the eighty-seventh episode overall. It aired on April 17, 2018.



Barry and Ralph investigate the wrecked bus in the hope of finding a clue to the whereabouts of the last bus meta, Edwin Gauss. Barry is shocked when Ralph suggests killing DeVoe as an option, saying they don't do that. Using dark matter scanners, they find a trace of Gauss. Ralph claims to have paid his fare (although in fact the opposite is true). Barry says it's as if he was there one second and not the next.

Harry calls them back to STAR Labs where he tells them, Iris, Cisco, Caitlin and Joe that he has developed the "sonic scepter", which duplicates Izzy Bowin 's powers, the only thing that has hurt DeVoe, and has no technology so can't be hacked. One burst will disable, a second will kill. He has also worked on an algorithm to predict DeVoe's next move. Joe talks with Cisco about how much Harry is using the Thinking Cap.

Caitlin tells Iris she has worked out how to bring out Killer Frost: Her dark matter is centred on her adrenal glands, so a shot of adrenaline will do it. She also reveals she and Killer Frost now communicate with notes. They then get an alert of a portal opening. The Flash, Elongated Man, Vibe and Frost head down there but find not DeVoe but Gauss, who casually posts a letter and then, startled by them, disappears back into a portal.

Cisco explains Gauss can create pocket dimensions like DeVoe. Iris realises if DeVoe has Gauss' powers, he won't need the chair to create portals anymore. Harry isolates which portal activity was down to Gauss, something Caitlin and Cisco thought impossible, and Iris decides they should split up and search, with Harry staying to mind the lab. Joe quizzes Harry about how much he uses the thinking cap, wondering if he's addicted. Harry says Cisco expressed concerns but he promised not to use dark matter. Joe sees him enter the Time Vault.

Barry, Caitlin and Ralph check out one of the locations and meet hippies who refer to Gauss as the Folded Man. Barry and Ralph again debate killing DeVoe if they can't capture him, with Barry insisting there's always another way. Caitlin locates Gauss, and Barry tells him they're there to protect him. They are then attacked by a Samuraizord, who impales Caitlin through the shoulder. Barry dismantles it at super-speed and carries Caitlin away.

Caitlin is soon recovered at STAR Labs, having frosted out. Ralph is angry that Barry and Iris consider getting Gauss to the pipeline a success and have no plan other than trapping DeVoe in there. He ends up speaking with Edwin, who reveals he once opened a portal into DeVoe's lair.

Harry storms into Cisco's lab searching for his thinking cap, trashing the lab and accusing Cisco of taking it. Joe appears with the cap and tells Harry to think about how he's treating the people he cares about. Meanwhile, Elongated Man, equipped with the sceptre, asks Gauss to portal him to DeVoe's lair. They are interrupted by the Flash. Elongated Man hides the sceptre inside his body but, after a brief fight, the Flash knocks him out.

Ralph recovers in sickbay. Barry tells Ralph that killing DeVoe would undo the man he's become. Ralph reveals he's most worried about DeVoe killing the rest of Team Flash. Barry says they all like having Ralph the way he is. Barry and Iris address the rest of the team: They want to adopt Ralph's plan of getting Gauss to portal them to DeVoe's lair but only if the others agree. Joe, Cisco, Harry and Caitlin all vote in favour.

Gauss sends the Flash, Vibe and Frost to the lair, with instructions to bring them back in fifteen minutes. However, the only DeVoe there is a hologram. The real DeVoe and Marlize arrive in STAR Labs. Iris, Joe and Harry find themselves locked out of the systems but Iris manages to blow their way out of the room they're in. They are confronted by a Samuraizord. Joe takes it on while Iris goes to find DeVoe's chair and Harry goes to get equipment needed to reprogramme it.

Ralph confronts DeVoe, who grows a dinosaur skeleton to full size and has it chase him through the pipeline. Harry takes his cap instead of the equipment he was meant to be getting and goes to the Time Vault, telling Gideon to charge it despite warnings. It overloads. Ralph defeats the dinosaur with an enlarged fist but finds DeVoe now possessing Gauss, standing over the bodies of Izzy, Matthew and Janet. Ralph takes the spectre from his body and hits DeVoe with a blast, preparing to deliver a second one.

Iris battles Marlize over the chair and ends up deliberately impaling herself through the shoulder on Marlize's sword, knocking her out and sending her and the chair back to the pocket dimension. The Flash, Vibe and Frost reappear, as Joe reveals he’s destroyed the Samurai zord. The Flash goes looking for DeVoe and finds Ralph has him in handcuffs. However, they're not working: DeVoe uses Petty's gravity powers to paralyse both Barry and Ralph, then transfers himself to Ralph's body, also turning on the monitors so Iris, Joe, Frost and Vibe can all see. Vibe transports himself and Frost there, and the Flash manages to pass through the floor and rejoin the battle, but DeVoe takes them all out, turning Killer Frost back into Caitlin, before portalling out.

Iris looks at the wall of bus-metas, saying they were meant to save them. Barry, Joe and Cisco are equally despondent. Barry super-speeds away and Iris goes after him. Caitlin asks Cisco and a confused Harry to examine her. They find nothing wrong but when Cisco uses a dark matter scanner on her, he realises DeVoe drained her powers: Killer Frost is gone. Iris finds Barry packing up Ralph's office at normal speed. He says he isn't ready to talk and Iris leaves. Barry raises a glass to Ralph's chair and says he'll look after them.

DeVoe and Marlize celebrate their success. DeVoe reveals that not only is Ralph's body not going to degenerate, but he can reshape it into a duplicate of his original body. He also produces a canister of dark matter, siphoned off when Harry was charging his cap: This will light the fire of Enlightenment.



Guest starring[]





  • The title of this episode directly relates to several characters and their respective plot points of the episode: Harry becomes addicted to using the Thinking Cap and in doing so alters his mind and attitude, Caitlin loses her Killer Frost abilities after finally starting to connect with her alter-ego, and Ralph, Edwin Gauss, Matthew Kim and Janet Petty are absorbed by DeVoe.
    • The title of this episode is inspired after Eminem's famous hit song "Lose Yourself" from 8Mile.
  • Gauss refers to Ralph as "Magnum, P.I.", referencing the TV series of the same name.
  • Cisco constructs a model of the USS Enterprise, a starship from the Star Trek franchise. He also uses a Scottish accent, referencing original series character Montgomery "Scotty" Scott.
  • When Harry throws around items looking for his Thinking Cap, Cisco calls him "Captain Caveman", referencing the title character from the TV series Captain Caveman and the Teen Angels.
  • After Barry knocks Ralph out, Ralph describes him having gone "Thor, son of Odin" on him, using an English accent. This is likely a reference to the Marvel Cinematic Universe character of the same name.
  • Cisco describes Joe to have gone "all John McClane" in a speech, referencing the protagonist of the Die Hard franchise.
  • When Gauss is describing The Thinker's lair and both DeVoes, he refers to DeVoe as looking like Professor X. This is a reference to the Marvel character Charles Xavier/Professor X.
  • DeVoe uses Dwarfstar and Black Bison's powers to enlarge and animate a miniaturized T-rex skeleton and sends it after Ralph, saying "An old friend requests a rematch". This is a reference to the events of "When Harry Met Harry...", which featured a confrontation between Ralph and an animated T-rex skeleton, an incident reminiscent of the movie Night at the Museum.
  • Before mounting his defense against the T-Rex bones, Ralph says, "Warning, fists in the pipeline are larger than they appear." Similarly, in the original Jurassic Park, when a full-fleshed T-Rex was pursuing a Jeep, the dinosaur appeared in the exterior rear view mirror of the Jeep. The mirror had the warning "Objects in the mirror may be closer than they appear."


  • When Ralph and Barry board CCTA405 at the impound yard, the interior advertising panels are lit, but the bus is not running.