The CW have released the synopsis for the upcoming third episode of The Flash, "Things You Can't Outrun."

And it's quite a bit of DC goodness, with a flashback revealing the apparent death of Ronnie Raymond and the emergence of Kyle Nimbus, the villain best known as The Mist.

The episode, which airs on October 21, will feature the first onscreen appearance of both characters unless one or both is teased in Episode Two and wasn't announced. It sees a lot of characters dealing with their baggage, including Detective West going to see Henry Allen in prison for the first time since arresting him years ago.

You can check out the official synopsis below. The Flash debuts next Tuesday, October 7, at 8 p.m. ET/PT on The CW.

THE FLASH BATTLES THE MIST, CAITLIN TELLS BARRY ABOUT RONNIE — As Barry (Grant Gustin) and the team at S.T.A.R. Labs work to capture Kyle Nimbus (guest star Anthony Carrigan), a.k.a. The Mist, a dangerous new meta-human with toxic gas powers, they revisit the painful night the particle accelerator exploded and killed Caitlin’s (Danielle Panabaker) fiancé, Ronnie (guest star Robbie Amell). Meanwhile, Joe (Jesse Martin) decides to finally visit Henry (John Wesley Shipp) in jail after all these years, but things take a dangerous turn when Kyle shows up looking to punish Joe for arresting him years ago. Meanwhile, Iris (Candice Patton) and Eddie (Rick Cosnett) continue to hide their relationship from Joe. Jesse Warn directed the episode written by Alison Schapker & Grainne Godfree (#103). Original airdate 10/21/2014.