“Think Fast” is episode twenty-two of season four of The Flash.
Digg turns up at an A.R.G.U.S. black site and passes through security. Which is unfortunate, as he’s DeVoe. DeVoe easily takes down all the guards at the facility using his powers before taking over the systems. This is the site where Fallout is being kept.
Barry has checked out all the launch sites at the right latitude DeVoe needs to launch his satellites and found nothing. Cisco suggests they stake out the launch sites separately. Barry points out they’re rather short of people. And Harry enters, barely functional intellectually and tripping over chairs.
In the previous episode, “Harry and the Harrisons”, Iris wrote and published an article about DeVoe and she’s keeping track of DeVoe and Marlize sightings. Because Marlize is just as dangerous. Barry is worried they’re sending people into danger; Iris says she’s inspiring them. Then gets a new message, corrupted by KILLG%RE, about Fallouts.
Caitlin is talking to Dr Finkel about Killer Frost without actually talking about Killer Frost. Finkel thinks she has dissociative identity disorder caused by trauma. Not in her adult life but something from childhood that Caitlin is repressing. Then Caitlin gets a message.
In the Cortex, Cisco unscrambles the message which says DeVoe is coming for Borman. Barry rushes to get Digg, and the others get something for Digg to throw up in. Digg says that Fallout is in a placed called the Castle. He agrees to remotely check on it and everything is fine. Except that Digg is also there. Fallout has now gone critical and can’t be saved. DeVoe is going to use him as a nuclear battery, shrinking Fallout’s cell and using him to charge the satellites. Launch is in 12 hours.
Barry wants to go to the Castle but it’s still protected by its defences. Including some electrical plates. Barry thinks he can enter flashtime and hit them fast enough to get a charge to make him fast enough to follow DeVoe. This will cause an electrical explosion and there are A.R.G.U.S. agents above the captive plates.
Joe is getting things ready for the hospital and Cecille is reassuring him when she suddenly starts acting very odd. In fact, she’s talking like the delivery guy who turns up moments later.
Iris is looking for Marlize and Harry tells her she needs to focus on feelings, not facts. Marlize will be where she feels safe. He wants to help Iris investigate.
Caitlin and Cisco think they’ve found a way to save the agents. Bring them into flashtime, as they’ve done some research and they can remain in it, briefly, without him touching them. They’ll have just enough time to rescue the hostages and for him to go after DeVoe.
They have mere hours to train for this, though, and Barry is feeling guilty. Harry is erratic, Cecille is acting strangely and Caitlin is repressing something.