Sara Jane finds solace by talking with her friend Liza May, who lives in her mirror. Her stepfather is impatient with her and says Liza May doesn’t exist. He’s irritable because something is killing his cattle. He thinks it may be an alien, but Sara Jane’s father, Dr. Livingston, is convinced it’s his invention, the LB23, which has escaped its controls and is ravaging the countryside. The LB23 attacks Sara Jane’s stepfather as her mother looks on, frying him. When Sara Jane heads for the lake, her father becomes concerned, knowing that the LB23 attacks anything shiny, such as her mirror. He tries to rescue her, but fails. She escapes, but the LB23 turns on its inventor, with horrifying results.