"Run, Iris, Run" begins with Cisco and Wells brainstorming ways on how to protect the remaining three metahumans that were on the bus.
Wells calls the group together and starts telling them a plan that involves an "intelligence booster," an invention he thought of that would boost the intelligence of whoever wears the cap.
In order for the cap to work, Wells would have to be exposed to lethal amounts of dark matter. Iris and Caitlin agree with the process, but Cisco disagrees and refuses to help Wells on what he considers a suicide mission.
Upset that the team finally has a way to stop DeVoe but can't agree on using the cap, Ralph Dibny storms off. Following him to try to talk him down, Iris is unable to speak some sense into Dibny, who leaves STAR Labs.
Barry and Joe are talking over a cup of coffee at Jitters. Joe reveals to Barry that the mayor of Central City wants to talk to DeVoe, and Joe tells Barry that Ralph needs to impersonate The Thinker once more.
At the Central City bank, a robber is using his fire-based powers to break into a safe. He's soon approached by a bystander, who tries talking him down from doing it. The two scuffle, and it's revealed that the bystander was able to remove the powers from the fire-wielding villain.
Cisco and Joe are on location at the bank examining the melted vault door. While questioning the apprehended robber, who claims he's been a metahuman for years, not making him a "bus meta," the pair discovers that the robber's powers no longer exist. They were taken by the bystander who stopped the robbery earlier.
At STAR Labs, Dibny is helping Wells put together his intelligence cap, which ends up on fire after a brief test run.
Joe and Iris head to the hospital, where they're looking at questioning an EMT named Matthew Kim — the ID of the bystander who stopped the robber earlier in the day. Kim admits to being at the scene, and he gets paranoid that Joe and Iris are trying to steal his powers.
Kim takes Iris hostage holding a scalpel to her throat when Barry rushes in to save her. In the ensuing scuffle, Kim's powers cause Barry to lose his speed and instead, transfers the power to Iris.
The team runs tests on Barry and Iris and discover that Kim swapped the metahuman DNA from Barry to Iris. Caitlin decides to work on a way to fix the mishap while Dibny, Joe, and Cisco work on a plan on trying to use Kim to take away DeVoe's powers.
The alarm at STAR Labs starts going off, and they find out a skyscraper downtown is on fire. There are people trapped on the top floor that the fire department can't reach.
Iris speeds off to the fire and saves the people, but when she goes back inside the stop the fire, she gets trapped under debris. Cisco vibes to the building to save her.
The next morning, the team meets to go over their plans. Caitlin reminds them that until she's able to reverse Iris' powers and give them back to Barry, Iris will have to remain the team's speedster.
Barry's training Iris when the STAR Labs alert starts ringing again. Melting Pot's powers have been transferred to a new meta — one of the people at the bank robbery we saw earlier — who's currently in a standoff with Joe and a squad of police officers. Iris runs to the scene to help out.
The new Melting Pot has started creating a thermal cyclone, and the group has run out of ideas to stop the thermal cyclone from spreading. Wells puts on his re-done intelligence cap and comes up with a plan that consists of Iris creating a tidal wave to douse the thermal cyclone.
After a minute, Iris is able to create the needed tidal wave and stops the villain from causing any further harm.
The group finds Matthew Kim and convinces him to switch the speed powers between Iris and Barry again. After filling Kim in on DeVoe, he decides to help Team Flash try and take down The Thinker.1comments
Barry and Iris are talking about the power switching at their place later that night, and Iris shows her husband that she's restarted her Flash-tracking blog.
Cisco and Wells are testing out his intelligence cap again, and after pushing it to its limit, Wells reveals the names of the final two bus metas in an almost catatonic-like state.