Supergirl, “Alex:” This episode focuses on Kara’s adopted sister and her partner, and the examines the effects of the mere existence of a metahuman.
The Flash, “I Know Who You Are:” this episode brings a new member into Team Flash and spends a lot of time on unconvincing personal drama. Thanks in part to his trip to the future, Barry deduces the identity of Savitar, and confronts him in the episode’s final moments.
Of course, we know now that the future can be changed.
Arrow, “Underneath:” Oliver and Felicity bunker down; Diggle and Lyla need couples counselling.