Kara deals with the loss of Mon-El by focusing her energy on being Supergirl and concentrating on a mysterious new threat. Alex confesses a secret to Maggie. A citizen of National City has a mysterious connection to Kara. Lena makes a bold move.
Kara and Alex 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.