“Lose Yourself” is episode eighteen of season four of The Flash.
Barry and Ralph are looking for clues about the last bus meta, Edwin Gauss, on the bus itself. Ralph talks about dealing with DeVoe. Permanently. Barry says the most important lesson for being a hero is that you never have to kill. With their abilities, there’s always another way. They find the seat where Edwin was; Ralph remembers him as he paid Ralph’s fare. Looking at the residual dark matter, it seems that Edwin was there and then gone. Then Harry calls them back.
Harry has come up with something to defeat DeVoe. Which mimics Izzy’s powers. Caitlin accurately calls it a big tuning fork. There’s also no tech involved, so it can’t be hacked. Harry also thinks he can get DeVoe’s next location with his thinking cap. Joe speaks to Cisco about Harry’s use of the cap afterwards.
Caitlin has been working on what activates Killer Frost. She tells Iris she’s worked out it’s adrenaline. Which means no more need to be traumatised when an epi pen will do the trick. And she and Killer Frost are communicating by notes. Then they get word a pocket dimension is about to open.
They breach there before it opens, but it doesn’t look like one of DeVoe’s. It’s not. Edwin Gauss comes through, posts a letter, gets startled and falls back through another. Back at the lab, it seems Edwin can use his own pocket dimensions; with his powers, DeVoe won’t need his chair. Harry can separate out the locations of pocket dimension openings and shows which were opened by Edwin. They’re going to check them out and Joe follows Harry. And talks about the cap and whether it’s dangerous to use. Very dangerous. Harry insists he’s not overusing it. Or addicted. Joe leaves, but he’s not fully gone, and he sees Harry go into Thawne’s secret room like he did in the previous episode, “Null and Annoyed”.
Barry, Ralph and Caitlin track down Edwin at a hippy community. They find him and tell him they’re there to protect him. The Samuroid that arrives, not so much. It’s defeated, though, and back at S.T.A.R. Labs, Caitlin checks herself out. Ralph is still concerned because DeVoe is ahead of them at every turn. Because the plan is always the same.
Ralph heads to the pipeline with a snack, and Edwin starts talking to him. And, it turns out, Edwin accidentally ended up in the Thinker’s lair.
Ralph wants to kill DeVoe. But because he’s worried about everyone else, not himself. Harry is certainly displaying signs of addiction with the thinking cap and he’s behaving foolishly. And the Thinker is still outthinking them.