Physicist Ted Hall is recruited to join the Manhattan Project as a teenager and goes to Los Alamos with no idea what he'll be working on. When he learns the true nature of the weapon being designed, he fears the post-war risk of a nuclear holocaust and begins to pass significant information to the Soviet Union.

Chronicling the lives and covert activities of the so-called "atom spies" in the 1940s, including the big one that got away, Theodore Alvin Hall.