The Flash and Supergirl share DNA insofar as they’re both part of the same superhero family on the CW, but they also, in a way, share a parent: Glee. Grant Gustin and Melissa Benoist — the titular heroes of each respective show — are both alumni of Ryan Murphy’s musical bildungsroman, and they get to remind us of it once more this week. The two series are crossing over for a musical two-parter in which each star will get to belt and lilt, and we have an exclusive clip of a scene in which we find Supergirl herself, Kara Danvers, singing the timeless “Moon River.” Watch, listen, and melt.