In 1947 New York, Chief Jack Thompson and Agent Peggy Carter of the Strategic Scientific Reserve (SSR) apprehend Soviet spy Dottie Underwood. Newly appointed Chief Daniel Sousa of the Los Angeles SSR office meets with Detective Andrew Henry, who has discovered a woman’s body in a frozen lake during a heat wave. Sousa, doubting his inexperienced agents, asks Thompson for backup; he sends Carter. An autopsy shows that the body glows in the dark, likely caused by Isodyne Energy’s particle accelerator. Carter learns from Isodyne scientist Jason Wilkes that the woman, physicist Jane Scott, had an affair with Isodyne owner and prospective senator Calvin Chadwick. Underwood is taken into FBI custody, with Thompson’s mentor Vernon Masters warning him of greater forces than the SSR that may affect his future.
