FORMER SUPERGIRL HELEN SLATER GUEST STARS – Clark (Tom Welling) learns Kara (Laura Vandervoort) is in Washington searching for the crystal. Kara is captured after she breaks into the lab and sedated with a kryptonite-infused truth serum. The serum causes her to relive a prior trip to Earth when she followed Clark’s biological mother, Lara (guest star Helen Slater), to the Kent farm. Clark arrives in time to save her but, after searing the machine with heat vision, he also falls victim to the serum and sees what Kara sees: his mother.
LEX DECIDES TO UNDERGO RADICAL TREATMENT TO REGAIN HIS MEMORY – Believing that key information about his father’s past was lost when his memory was erased, Lex decides to join an experimental program with Dr. Garner to regain the information so he can turn his father over to the FBI. Knowing that Lex will discover his secret if he regains his memory, Clark tries to stop him but is caught by Lionel and the doctor and exposed to the same radical treatment so that Lionel can solve the mystery of Clark’s past.