Previously on The Flash: it was the end of everything! Nash Wells (Tom Cavanagh) unwittingly released The Anti-Monitor (LaMonica Garrett)! The CW’s Crisis on Infinite Earths saw the end of the multiverse and the birth of a new one, sparked by the dying sacrifice of Oliver Queen (Stephen Amell) and infused with the qualities of the seven Paragons, including Barry Allen, aka The Flash (Grant Gustin)! The Monitor (Garrett) prophecy that The Flash must die during the Crisis came to pass—but it was The Flash of Earth-90 (John Wesley Shipp) who laid down his life to save billions! With the Crisis over, and Barry still alive, what awaits him and the rest of Team Flash? In The Flash S6E10, “Marathon,” Barry and his friends have trouble adjusting to their literal new reality, and the arrival of a new foe portends bad things for our heroes through the second half of the season.

Run, Cougar, Run

The episode opens at C.C. Jitters, a banner waving that they’ve just reopened after the crisis. As a barista serves drinks, a man toting a giant gun yells that he’s robbing the place. Across town, at S.T.A.R. Labs, Cisco Ramon (Carlos Valdes) and Killer Frost (Danielle Panabaker) get an alert that Jitters is being attacked, and over comms Barry says he’ll take care of it. At Jitters, the barista explains to the armed man that there’s very little money in the register, considering they just reopened, so he starts firing wildly. Suddenly The Flash arrives, rescuing the civilians and wrapping up the gunman in the aforementioned banner. The assembled people applaud for him, and The Flash smiles.

After a spiffy new opening credit sequence, we’re back at S.T.A.R. Labs. Cisco is working on mapping the post-Crisis Earth, both physically and in terms of its timeline. Frost (no longer Killer) finds him working, and asks why he still seems so stressed with the Crisis over. Cisco responds that there are so many things they still don’t know, and he presents a binder of trading cards featuring villains he recognizes and others he doesn’t, but who’ve arrived as a result of the merged earths. Nash, who Cisco had locked in a closet as a goof, enters, and Cisco gives him another cryptocircuit (Nash loves those things). Nash says he’s going to run tests at his dig site to make sure no one ever accidentally opens the anti-matter universe again, but Cisco says he’s already run tests, and that they don’t need Nash. As Nash exits, Frost flips through the trading cards.

Barry arrives home to find Iris (Candace Patton) basking in the Central City Citizen’s success, specifically on a story about The Flash stopping the crisis. Barry tells her he ran into a friend on the way home, and John Diggle (David Ramsey) enters (this episode takes place before Diggle gets his Green Lantern ring). He explains that Oliver’s will was just read, and he presents Barry with a box left for him by Oliver. Inside is Oliver’s first mask, the Barry made for Oliver years ago. Barry notices a mark on the mask and immediately thinks it might be a clue Oliver left for him to a new threat, but Diggle doesn’t buy it, and Iris sort of sighs. Her phone buzzes, and she says she has to leave to meet a source. Barry says not to worry, and that he and Diggle will work on this clue.

Shortly, in a parking garage, Iris meets her source, a former employee of McCulloch Technology. She shows him a photo of a swirl symbol on her phone, and he recognizes it. He tells her about the theft of a prototype infrared photon rifle from McCulloch Tech, and that he was fired for asking questions about it and the man he suspects stole it. Iris shows him a photo of the charred corpse of the thief, and promises that she’ll keep the source anonymous if he’ll help bring the people who did this to light. He tells her about the people he believes is behind the theft, saying that it’s an organization called Black Hole. As he talks, the viewer sees a woman in a silver coat, with purple glowing eyes, carrying the photon rifle and chasing a man through a lab. She corners the man and fires the rifle, disintegrating him. Her phone rings, and a male voice speaking Japanese says he has her next target. She looks at her phone and sees a photo of Iris.

Never A Dull Moment

Back at the Central City Citizen, Iris and her team — Kamilla Hwang (Victoria Park) and Allegra Garcia (Kayla Compton) are filling in Cecile Horton (Danielle Nicolet) about what they know about Black Hole. The organization has been operating in Central City for seven years, abducting and training metahumans like Allegra’s cousin. Cecile urges them from a legal perspective not to run the story, saying they could be sued by McCulloch Tech for defamation. Iris says she’s willing to take that risk, and she and the others make a lot of statements about reporters not walking away from stories. Iris has a meeting with McCulloch Tech CEO Joseph Carver (Eric Nenninger) later, but she tells Allegra and Kamilla they’re going to run the story with or without his comment.

Back at Barry & Iris’s apartment, Diggle is sitting quietly while Barry brings his lab equipment to the apartment (Diggle didn’t want to run there). Diggle tells him to slow down, but Barry ignores him. Analysis of the mask reveals mirakuru, the super-soldier serum that created Deathstroke, on the mask. Barry says they need to go to Lian Yu to find and destroy the last stash of mirakuru before it can fall into the wrong hands. Diggle takes a dramamine or five, and the two speed off.

At McCulloch Tech, Iris interviews Carver, who describes starting McCulloch Tech with his wife, Eva McCulloch, now deceased. Iris tells Carver what she knows about the theft, and the stolen weapon’s link to numerous crimes. Carver takes Iris into a secure area, and tells her he knows who her source is. He presents her with the man’s HR file, and says the rifle was stolen by Obsidian Tech, not some terrorist organization. He tells her there’s no story here, and she disagrees. Carver then asks her not to run the story, and Iris refuses and leaves.

Back at the Citizen office, the story is up, and the team is celebrating. Cecile arrives and tells everyone they’re being sued by McCulloch for defamation. Outside and across the street, the silver-coated assassin aims the rifle at the Citizen. Cecile senses that something’s not right, while Iris goes on and on about the truth. Cecile tells everyone to get down just as a rifle blast hits the wall behind them, disintegrating part of the wall. Iris tells the others to get to S.T.A.R. Labs, and that she’ll escape through Nash’s tunnels and check on the safety of her source.

At S.T.A.R. Labs, Kamilla and Allegra arrive. Cisco says he can’t raise Barry, since reception on Lian Yu is nonexistent. Allegra asks if they can use a breach extrapolator, but Cisco says they don’t work in the new universe. Kamilla, who snapped a picture of the wall damage, says whoever tried to kill them was using high-intensity light. Nash enters, concerned for Allegra, and is immediately angry that Cisco didn’t tell him anyone was in danger. The two argue, with Cisco berating him for only coming around when he needs something, and for starting the Crisis by freeing The Anti-Monitor. Nash says he’s paid for his sins, and Cisco counters that that doesn’t help everyone who died. Nash leaves, and Kamilla asks Cisco what’s going on. He says he’s making sure they learn from their mistakes, and that they need to find Iris.

Back at the parking garage, Iris meets with her source again. He draws a flash drive from his pocket, but before he can hand it to her he’s shot by the photon rifle and disintegrates. As he’s dying, he pushes Iris out of the way and says “mirror.” Iris grabs the flash drive off the ground and jumps into his car. After Iris tries to run her down, the assassin shoots out the back window of the car. Glass affected by the gun hits Iris’s arm, wounding her, and she drives away.

Now You See Him, Now You Don’t

Having returned to S.T.A.R. Labs, Iris looks through Cisco’s villain trading card binder and finds the assassin: Dr. Kimiyo Hoshi (who they dub Doctor Light), a metahuman with the power to funnel star light. Cisco says Hoshi has been missing for four years, and Kamilla suggests she’s using the rifle to focus her powers. Cisco is frustrated at this new Earth presenting even more surprises, and Iris pulls out the flash drive to find it broken. Taking off her coat and revealing her wounds, Iris insists she’s fine, then collapses.

On Lian Yu, Barry and Diggle find a box for mirakuru in the old A.R.G.U.S. facility on the island. Barry opens the box, but there’s nothing in it. Frustrated, he insists there’s more to it and says he has to finish what Oliver started, his hand sparking with lightning momentarily. Diggle asks if he’s alright, and Barry says that’s never happened before. Diggle tells Barry about Oliver having faced Deathstroke on Lian Yu, and says that’s probably how the mirakuru ended up on his mask. He says Barry’s looking for something that doesn’t exist, and Barry says he has to protect this Earth so that Oliver won’t have died in vain. Diggle tells him Oliver gave his life so the people he loved could live theirs. He calls life a marathon, not a print, and suggests Barry needs to slow down and appreciate it.

At S.T.A.R. Labs, Caitlin (now de-Frosted) checks on Cisco, who’s watching a message from the Harrison Wells of Earth-2 (though in this timeline Harry never existed, so how does Cisco still have this? Wibbly wobbly). Cisco tells her he blames himself for his friends being gone, and wonders if he hadn’t stopped being Vibe if he might’ve been able to stop the crisis or at least save more people. Caitlin asks if he regrets taking the cure, and he says no, but that it’s not that simple. Caitlin tells Cisco his idea to compile data and track the changes on the new earth is a good idea. Cisco responds that he can’t do that from here, and Caitlin agrees, suggesting that some time away might help him figure out who he wants to be now that the crisis is over.

Elsewhere, in the infirmary, Iris is watching TV when her father, Joe (Jesse L. Martin), enters to check on her. He’s upsect with her for running the McCulloch Tech story and putting herself in danger. Iris says she has to expose the people who attacked her friends and killed her source, and Joe says he agrees, but that she won’t be able to solve this in one day. He says they don’t have to live in crisis mode anymore, and that they have time to do things and she should slow down. Joe asks if her source told anyone else about Black Hole, and she says no before realizing that Carver knew about them.

The Black Hole

At McCulloch Tech, Carver is revealed as the voice on the other end of the phone calls to Doctor Light, who at that moment is standing outside of Joe West’s house. Inside, Joe and Iris are settling in. Hoshi enters silently, and fires the rifle on Iris. The blast passes through her, and the hologram of Iris disappears. Joe pulls out a shotgun, and Frost appears as well wielding ice daggers. Back at McCulloch Tech, the real Iris confronts Carver, who is preparing for a press conference. She says she has evidence linking McCulloch Tech to Black Hole, that he orchestrated the ‘theft’ that put the rifle into the hands of Doctor Light, and that he is Black Hole himself. Carver says she doesn’t have the whole story or she wouldn’t be there trying to scare him while her family risks their lives. Iris says he’s right, but that if any harm comes to her or her family or friends, a dead man’s switch will release everything she has on him and Black Hole.

Meanwhile, back at Joe’s house, Doctor Light throws a big bowl at Joe, knocking him down, and fires her rifle on Frost, who staggers back. She fights back against the bullet eating away at her, and is able to extract it from her chest. As Light prepares to shoot Frost in the head, she gets a call from Carver to stand down. She immediately exits, while back at McCulloch Tech Carver announces he’s dropping his lawsuit against the Central City Citizen.

Later, at S.T.A.R. Labs, Cisco is packing stuff from his lab for his trip. Nash enters, and Cisco asks him if he’d be up for filling in for him while he’s away. Nash at first thinks it’s a trick, but Cisco apologizes for what he said before, and for taking his guilt out on Nash. He and Nash joke a bit, beginning to form a bond, and as Cisco exits he says he hopes Nash finds what he’s looking for. Alone in the lab, Nash pulls out a photo of himself and someone who looks like Allegra.

At Barry & Iris’s apartment, the two fill each other in on their days, and their shared realizations that they both need to slow down. The crisis is over and Barry survived, and they agree they need to savor that. They agree to take the night off.

Later that night, Iris is awake in the darkened apartment. She sees a nearby mirror, and remembers what her source said as he died. She also remembers a room she saw at McCulloch Tech labeled ‘AV3.’ Writing down the room label, she holds it to the mirror and discovers it spells ‘EVA’ (as in Eva McCulloch). She hastily writes a note for Barry and leaves.

At McCulloch Tech, Iris breaks into the facility using her source’s old ID card. The door to room AV3 has no lock on it, but Iris pulls out the Black Hole button Allegra found a few weeks ago. Holding the pin to where the lock should be, the door opens. Inside she finds what looks like an office, with sheets covering all the furniture. Removing sheets, Iris starts photographing everything, including documents on the desk and images on the computer screen. She pulls down another sheet to reveal a floor-to-ceiling mirror behind the desk. A notification on the computer causes Iris to turn from the mirror, and as she does a pair of mirrored arms stretch out from the surface of the mirror and pull Iris in.

Fans of the Central City Citizen will surely enjoy this episode, as it mainly focuses on that team and their journalistic endeavors. Fans of The Flash…maybe not so much. Coming out of the gate post-Crisis, this was a pretty slow start to the next half of the season. It makes sense that it would be that way—there’s a lot to unpack following the creation of a new Earth, and Team Flash is definitely the team to unpack that. I just wish there’d been more unpacking, more exploration, and more Flash action, instead of Barry running off with Diggle on a wild mirakuru chase. Hopefully next week the pace will pick up as Barry searches for his missing wife.