Last week, Barry (Grant Gustin) and Iris (Candace Patton) told Team Flash about their visit from The Monitor (LaMonica Garrett)—and about The Flash’s impending demise! Plus, Barry met Dr. Ramsey Rosso (Sendhil Ramamurthy) for the first time, and Rosso learned he can control dark matter-infused blood! What next moves will Rosso make in his quest to cure death itself? And what preparations will Team Flash make for a potential world without the fastest man alive? The Flash S6E4, “There Will Be Blood,” is an appropriately horrific Halloween episode about the lengths one will go to to save a life, and to accept that some lives can’t be saved.

Blood Simple

As the episode opens, Rosso is at Central City Hospital. After some forced pleasantries with a colleague, Rosso enters a lab, where he appears to be weakened, staggering around and smashing things. He makes his way to a locked refrigerator and, his hand covering in thick dark matter-infused blood, he destroys the lock using apparent superstrength. Inside the refrigerator, Rosso looks over bags of typed blood.


At S.T.A.R. Labs, Barry, Iris, Killer Frost (Danielle Panabaker), and Cisco (Carlos Valdes) are sitting around talking about the coming crisis. Cisco insists they need to find a way to save Barry’s life, but Barry tells him there’s no other way, and Frost adds that if there was they’d be looking for it. A resigned Cisco leaves, and Barry gets a message on his phone from CCPD about the break-in at the hospital.

Barry arrives at the hospital and finds Captain Joe West (Jesse L. Martin) on the scene already. They discuss whether the robbery is meta-related, and Barry guesses that it’s not. Joe can tell something’s bothering him, and Barry says it’s the coming crisis and Cisco not dealing with it well. Joe says Cisco’s a lot like Barry and will always try to save people. As he exits, Barry thanks him and says he has an idea of how to get through to Cisco.

In his lab, Rosso dictates into a recorder. He says that absorbing Mitch Romero’s blood (which he did last week) temporarily cured his HLH cancer, but he needs more of the dark matter-infused blood in order to cure it permanently. He draws blood from himself and mixes it with the blood he stole from the hospital, placing it into the centrifuge. As it spins, Rosso reflects on his relationship with his mother, and on her own struggle with HLH.

Back at S.T.A.R. Labs, Barry tells Cisco that he understands how he feels, and that he can still save a life even in the face of the coming crisis. Cisco at first things Barry means himself, but Barry says they’re actually going to save Ramsey Rosso. Cisco at first scoffs, asking Barry if they’re going to spend the remaining time he has left curing everyone who has cancer, to which Barry responds that they just have to start with one. Cisco finally agrees, but is unsure how to proceed, when Nash Wells (Tom Cavanagh) appears in the window, having scaled the building. Wells offers to help, saying he needs an antivibrational crypto-circuit (this week’s science goober), which he says they can build in exchange for his help. Cisco and Barry sidebar, saying neither of them trusts this Wells, but that a Wells usually does show up for a reason. Nash reiterates that what he’s offering them can help save Ramsey Rosso’s life.

Iris arrives at the office of Ralph Dibny (Hartley Sawyer), P.I., with a present for him. She excitedly hands him a folder containing an eye-witness account she obtained from someone who saw Sue Dearbon, the missing person Ralph has been looking for for months. Ralph takes the folder and drops it on his desk before returning to reading a book. A confused Iris exits the office.

Having completed his centrigufing, Rosso injects himself with the new mixture of Romero’s blood and the blood he stole from the hospital. The serum reacts negatively with his own blood, bubbling black blood onto the surface of his skin, and Rosso falls to the ground, convulsing and whimpering that he’s failed.

The Dead Don’t Die

Outside of McCulloch Technologies (the location Nash was photographed breaking into last week), Nash tells Barry and Cisco that there’s a bioregenerative serum inside that can heal any organic tissue by replicating healthy cells to replace unhealthy ones. Barry and Cisco realize the serum, which was stolen from the Dominators following the invasion three years ago, would be extremely dangerous in the wrong hands, and agree to help Nash steal it. Barry exits the van at superspeed to take out the exterior cameras, and while he’s gone Cisco asks Nash if the serum would work on anti-matter, which Nash says it would. Barry returns, and the team breaks into the building. Inside, meta-dampeners around the facility neutralize Barry’s powers. After Nash dispenses with a couple of guards, the trio make their way further in, and Cisco plants something on one of the wall as they walk away.


At Ralph’s apartment, Iris asks him if he’s had any luck with the Dearbon lead. Ralph says he’s given up on it, gathering cupcakes and other sweets in his arms. He tells Iris that, if he were her, he’d be spending more time with her husband while he’s still around.

Back at McCulloch Tech, Barry, Cisco, and Nash find the refrigerated container that holds the serum. Cisco hooks up a tablet to the container and begins to hack it, pressing a button on the screen that sets off the device he planted earlier, now revealed to be an alarm. Nash and Barry rush out to hold off whoever’s coming, and Cisco opens the container, grabbing the serum and shoving it in his pocket before closing the container again. Barry returns and Cisco opens the container to reveal it empty, saying McCulloch must’ve sold it already. Nash rushes back in, with guards on his tail, and hands Barry and Cisco each a small silver orb, saying they are their way out. On three they all throw the orbs at the ground, and a plume of smoke appears, filling the room. When the smoke clears, the three of them are back at S.T.A.R. Labs. Nash asks them when they’re going to get to work on his cryptocircuit.

Back at Rosso’s lab, a frantic Rosso paces back and forth, desperate to figure out what he did wrong, throwing papers and books everywhere. As he despairs he remembers a conversation he had with his mother about the cure and the dark matter bonding agent. His mother rejects it, and Rosso says he won’t give up like she has, and that his true enemy is not her, but death itself.

At S.T.A.R. Labs, Cisco is working on Nash’s goober when Barry comes in to check on him. He questions whether they should give Nash what he wants considering they didn’t get anything from McCulloch Tech, and Cisco is strangely stoic. Barry then notices a small refrigerator, which Cisco says is for Frost’s stuff. Barry opens it to find the serum from McCulloch, and Cisco is defiant, saying Barry will have to go through him to get it. The two get into an intense argument, Barry shocked that Cisco would do something like that, and Cisco angry with Barry for refusing help to begin with. Barry tells Cisco he was trying to get him to make a tough call because that’s what leaders do, and that he wants Cisco to lead S.T.A.R. Labs and the team when he’s gone, but now he’s not sure he made the right call. Cisco reluctantly hands over the serum and walks away. Later, Barry visits Rosso’s lab and presents him with the serum, saying he wants Ramsey to feel like he has a lifeline. Rosso thanks him, a look of relief on his face.

Joe goes to visit Ralph in his office. Ralph tells Joe there’s no point in working the Dearbon case, asking what the point is of saving her if he can’t even save Barry. Joe gives Ralph a Classic Papa Joe Speech about something his old partner once said to him, that even if they can’t save everyone, they can at least save one person. Ralph says he’s going to miss Barry, and Joe looks away silently, and it is absolutely heartbreaking.

At S.T.A.R. Labs, Cisco hands the completed circuit over to Nash, who mocks the workmanship before leaving. Frost asks Cisco how it’s going, and Cisco tells her about his argument with Barry and what he thinks might be the end of their friendship. Frost tells him that he can’t save someone who doesn’t want to be saved, which Barry doesn’t. She advises him not to continue to try because it might lead him somewhere he doesn’t want to be.


Back at his lab, Rosso tests the serum on his blood, but it fails—his cells are too damaged already from all his previous experiments. Suddenly Rosso realizes the difference: Romero was afraid for his life when Rosso changed his blood, and the adrenaline acted as a bonding agent. He says that, in order to cure himself, he has to kill someone, and they have to be afraid first. The camera focuses on the Hippocratic Oath framed on Rosso’s wall, particularly the ‘do no harm’ clause, just to really drive home for the viewer that he’s doing stuff a doctor shouldn’t do. Rosso stalks out of the lab, his eyes turning black as he does.


Alarms trigger at S.T.A.R. Labs about an attack at Central City Hospital, and The Flash and Killer Frost arrive on-scene to stop the reported madman who’s attacking patients. They find a victim already dead, and Frost stays to investigate the body while Flash runs ahead to stop the screaming they hear down the hall. He finds Rosso feeding on another patient, and Rosso goes full supervillain speech on him about how he needs to feed in order to live. He then reanimates the bodies from which he’s already fed, using them to attack The Flash and Killer Frost. The heroes take them down with relative ease, and Rosso grabs a live doctor who had been hiding nearby, threatening to kill him and revealing that he was the doctor who he says let his mother die. Rosso rants about his humanity being a disease that he’s finally cured before slicing the doctor’s throat and leaping out a window. The doctor, now infected, rises and shambles away, his body liquifying into black blood as he does.

Back at S.T.A.R. Labs, the team talks about Rosso and what he’s become. Barry says he’s going to stop Rosso if it’s the last thing he does on this earth, and Ralph jokes about Halloween before leaving. Iris goes after him, and Ralph apologizes for being a jerk to her. He says he’s going to follow up on the Dearbon lead tomorrow, and Iris says Sue is lucky he’s looking for her, which Ralph dismisses, saying he’s not “looking to get married.”

Back in the breakroom, Cisco apologizes to Barry, who says at least they tried to do the right thing. Cisco says he doesn’t know how Barry does it, but that he understands Barry’s trying to teach all of them how to do it, and that that’s what it means to be a hero. He heads out, leaving Barry to talk to Joe, who looks absolutely destroyed. Barry asks if he’s alright, and they talk about finding Rosso before things get worse. Barry seems to blame himself for what’s happened to Rosso, but Joe tells him not to, that he’s done incalculable good as The Flash, and that he deserves better than to die. Barry tells Joe that he owes everything to him, and Joe breaks down, saying he’s not ready for Barry to be gone. Barry tells him he’ll always be with him, and embraces his surrogate father.

In an underground tunnel, Nash inserts the goober into his wrist-worn eternium detector. Pushing a few buttons, he is able to map out past movement of the element within the tunnel, which reveals an afterimage of The Monitor walking towards and apparently through a wall. “So that’s where you’ve been hiding,” Nash says to himself. He approaches the wall, removes a pickaxe from his satchel, and swings it at the wall.

This episode finally saw Ramsey Rosso fully embrace his dark side, giving Team Flash a supervillain unlike any they’ve faced before. It’s clear the team is also still struggling with the emotional weight of the impending Crisis, which feels appropriate given the scale of what’s coming and what they’re preparing to lose. Will they be able to move past their feelings in order to stop Rosso? And just what will Nash Wells find beneath the streets of Central City? We’ll find out next week!