Supergirl Season 3 Episode 4 - The Faithful br br Kara investigates a secretive new group whose leader, Thomas Coville, has a mysterious connection to Supergirl. Meanwhile, Samantha feels like she's letting Ruby down, and J'onn confesses an old secret. br br Supergirl 3x04 The Faithful - Inside doc br br The adventures of Superman's cousin in her own superhero career.