At Midvale High, Supergirl attends a science club meeting as Linda Lee, where a scientist is testing the possibility of humans with Extra-Sensory Perception. There, she notices that one girl, Lena Thorul, is getting every question right, which shouldn't be possible. She befriends her, and learns that Lena has been rejected by the F.B.I.
Investigating the reason for her friend's rejection, Supergirl discovers that Lena Thorul was the kid sister of Lex Luthor, and had lived with him in Smallville. She had gained her telepathic powers due to a shock from a Space-Brain in Luthor's lab, before it was destroyed.
Meanwhile, Lena gets involved with the Bank Busters, a criminal organization. Lex Luthor, in jail, hears about this and asks Supergirl's help to stop his sister from following in his footsteps. However, Lena turns out to have noble intentions when she betrays and defeats the criminals.