“Midvale” is the title of the November 13 episode of Supergirl and in it we meet a new Young Kara and Young Alex!
Here’s the official description with spoilers for the episode courtesy of The CW.
ESCAPE DOWN MEMORY LANE — Kara (Melissa Benoist) and Alex (Chyler Leigh) head home to Midvale for a little R&R. While there, Kara recalls a painful memory of a childhood friend’s death and how that traumatic experience brought the Danvers sisters closer together. Izabela Vidovic plays Young Kara and Olivia Nikkanen plays Young Alex in flashbacks. Rob Greenlea directed the episode written by Caitlin Parrish and Jess Kardos (#306). Original airdate 11/13/2017.