A classmate of Lana's, Seth, receives a head injury at the carnival from a green-k filled snowball, and during the MRI treatment the machine goes berserk and gives Seth magnetic powers. Not only can he manipulate metal but he can influence people's thoughts . . . and he starts with Lana. Clark becomes suspicious and follows them but Lana doesn't believe him. In addition Lana begins to act increasingly wild and Seth asks her to leave Smallville with him – she takes the money out of the Talon's till and leaves. Clark manages to stop them long enough for the sheriff to catch up but Seth flees leaving Lana holding the bag.
In jail Lana apparently snaps out of it and sends Clark on a wild-goose chase while Seth comes to her rescue. Clark uses a compass to track them to the carnival and the Tunnel of Love ride. Lana threatens to shoot Clark then Seth sends her out and tries to kill Clark – Clark manages to reverse Seth's polarity and defeat him. Lana eventually recovers for real and ends up doing community service and Seth ends up in a coma.
Meanwhile Lex pursues the investigation into his grandparents' deaths and learns that Chloe is also investigating his father Lionel. His private investigator takes her computer but he turns up dead of "natural causes" and Lex suspects his father and offers his help and protection to Chloe. Chloe reveals everything about her deal with Lionel and how she planned to try and blackmail Lionel to get out of their deal and let her father keep her job. Chloe reveals that Lionel and Morgan Edge were childhood friends.